diff --git a/Data.SeaHavenIndustries/Migrations/20260813160000_SH218_WorkOrderAdditionalContacts.cs b/Data.SeaHavenIndustries/Migrations/20260813160000_SH218_WorkOrderAdditionalContacts.cs
new file mode 100644
index 0000000..2ae18e8
--- /dev/null
+++ b/Data.SeaHavenIndustries/Migrations/20260813160000_SH218_WorkOrderAdditionalContacts.cs
@@ -0,0 +1,33 @@
+using Data.SeaHavenIndustries;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Data.SeaHavenIndustries.Migrations
+{
+    /// <inheritdoc />
+    [DbContext(typeof(ApplicationDbContext))]
+    [Migration("20260813160000_SH218_WorkOrderAdditionalContacts")]
+    public partial class SH218_WorkOrderAdditionalContacts : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<string>(
+                name: "AdditionalContacts",
+                table: "workOrders",
+                type: "nvarchar(4000)",
+                maxLength: 4000,
+                nullable: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "AdditionalContacts",
+                table: "workOrders");
+        }
+    }
+}
diff --git a/Data.SeaHavenIndustries/Migrations/ApplicationDbContextModelSnapshot.cs b/Data.SeaHavenIndustries/Migrations/ApplicationDbContextModelSnapshot.cs
index 813853c..45bd51c 100644
--- a/Data.SeaHavenIndustries/Migrations/ApplicationDbContextModelSnapshot.cs
+++ b/Data.SeaHavenIndustries/Migrations/ApplicationDbContextModelSnapshot.cs
@@ -2496,6 +2496,10 @@ namespace Data.SeaHavenIndustries.Migrations
                         .HasMaxLength(2000)
                         .HasColumnType("nvarchar(2000)");
 
+                    b.Property<string>("AdditionalContacts")
+                        .HasMaxLength(4000)
+                        .HasColumnType("nvarchar(4000)");
+
                     b.Property<string>("PocPhone")
                         .HasMaxLength(50)
                         .HasColumnType("nvarchar(50)");
diff --git a/Data.SeaHavenIndustries/Models/WorkerOrder.cs b/Data.SeaHavenIndustries/Models/WorkerOrder.cs
index 59f2390..ec2e450 100644
--- a/Data.SeaHavenIndustries/Models/WorkerOrder.cs
+++ b/Data.SeaHavenIndustries/Models/WorkerOrder.cs
@@ -54,6 +54,9 @@ namespace Data.SeaHavenIndustries
         public string? PocPhone { get; set; }
         [MaxLength(2000)]
         public string? PocNotes { get; set; }
+        /// <summary>JSON array of additional POC contacts beyond primary (name, phone, notes?).</summary>
+        [MaxLength(4000)]
+        public string? AdditionalContacts { get; set; }
         /// <summary>JSON array of extra service labels beyond primary (Trade).</summary>
         [MaxLength(2000)]
         public string? ExtraServices { get; set; }
diff --git a/SeaHaven.DataServices/Helpers/WorkOrderBoardProjection.cs b/SeaHaven.DataServices/Helpers/WorkOrderBoardProjection.cs
index 3d43fe3..afb9a82 100644
--- a/SeaHaven.DataServices/Helpers/WorkOrderBoardProjection.cs
+++ b/SeaHaven.DataServices/Helpers/WorkOrderBoardProjection.cs
@@ -66,6 +66,7 @@ namespace SeaHaven.DataServices.Helpers
                     w.Problem,
                     w.ServiceNotes,
                     w.ExtraServices,
+                    w.AdditionalContacts,
                     w.DocStatus,
                     w.CompletedDate,
                     w.FlagColor,
@@ -127,6 +128,7 @@ namespace SeaHaven.DataServices.Helpers
                     w.Problem,
                     w.ServiceNotes,
                     w.ExtraServices,
+                    w.AdditionalContacts,
                     w.DocStatus,
                     w.CompletedDate,
                     w.FlagColor,
diff --git a/SeaHaven.DataServices/Interfaces/WorkOrderBoardModels.cs b/SeaHaven.DataServices/Interfaces/WorkOrderBoardModels.cs
index ca27ca0..cc78030 100644
--- a/SeaHaven.DataServices/Interfaces/WorkOrderBoardModels.cs
+++ b/SeaHaven.DataServices/Interfaces/WorkOrderBoardModels.cs
@@ -46,6 +46,7 @@ namespace SeaHaven.DataServices.Interfaces
         string? Problem,
         string? ServiceNotes,
         string? ExtraServices,
+        string? AdditionalContacts,
         DocStatus? DocStatus,
         DateTime? CompletedDate,
         string? FlagColor,
diff --git a/SeaHaven.Services/DTOs/WorkOrderAdditionalContactDto.cs b/SeaHaven.Services/DTOs/WorkOrderAdditionalContactDto.cs
new file mode 100644
index 0000000..25c33d1
--- /dev/null
+++ b/SeaHaven.Services/DTOs/WorkOrderAdditionalContactDto.cs
@@ -0,0 +1,4 @@
+namespace SeaHaven.Services.DTOs
+{
+    public record WorkOrderAdditionalContactDto(string Name, string Phone, string? Notes);
+}
diff --git a/SeaHaven.Services/DTOs/WorkOrderBoardDTOs.cs b/SeaHaven.Services/DTOs/WorkOrderBoardDTOs.cs
index de3fe67..b720a9e 100644
--- a/SeaHaven.Services/DTOs/WorkOrderBoardDTOs.cs
+++ b/SeaHaven.Services/DTOs/WorkOrderBoardDTOs.cs
@@ -34,6 +34,7 @@ namespace SeaHaven.Services.DTOs
         public string? PocName { get; set; }
         public string? PocPhone { get; set; }
         public string? PocNotes { get; set; }
+        public List<WorkOrderAdditionalContactDto>? AdditionalContacts { get; set; }
         public LifecycleStatus? LifecycleStatus { get; set; }
         public string? LifecycleStatusLabel { get; set; }
         public string? LegacyStatus { get; set; }
diff --git a/SeaHaven.Services/DTOs/WorkOrderBoardRequestDTOs.cs b/SeaHaven.Services/DTOs/WorkOrderBoardRequestDTOs.cs
index 3ca672c..0087293 100644
--- a/SeaHaven.Services/DTOs/WorkOrderBoardRequestDTOs.cs
+++ b/SeaHaven.Services/DTOs/WorkOrderBoardRequestDTOs.cs
@@ -41,6 +41,7 @@ namespace SeaHaven.Services.DTOs
         public string? PocName { get; set; }
         public string? PocPhone { get; set; }
         public string? PocNotes { get; set; }
+        public List<WorkOrderAdditionalContactDto>? AdditionalContacts { get; set; }
         public string? TechPhone { get; set; }
         public string? VendorNotes { get; set; }
     }
diff --git a/SeaHaven.Services/Helpers/WorkOrderAdditionalContactsMapper.cs b/SeaHaven.Services/Helpers/WorkOrderAdditionalContactsMapper.cs
new file mode 100644
index 0000000..4fc2bc9
--- /dev/null
+++ b/SeaHaven.Services/Helpers/WorkOrderAdditionalContactsMapper.cs
@@ -0,0 +1,120 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using SeaHaven.Services.DTOs;
+using SeaHaven.Services.Exceptions;
+
+namespace SeaHaven.Services.Helpers
+{
+    public static class WorkOrderAdditionalContactsMapper
+    {
+        private const int MaxNameLength = 200;
+        private const int MaxPhoneLength = 50;
+        private const int MaxNotesLength = 2000;
+        private const int MaxSerializedLength = 4000;
+
+        private static readonly JsonSerializerOptions JsonOptions = new()
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+            PropertyNameCaseInsensitive = true,
+            DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
+        };
+
+        public static List<WorkOrderAdditionalContactDto>? ParseJson(string? json)
+        {
+            if (string.IsNullOrWhiteSpace(json))
+                return null;
+
+            try
+            {
+                var parsed = JsonSerializer.Deserialize<List<WorkOrderAdditionalContactDto>>(json, JsonOptions);
+                return parsed is { Count: > 0 } ? parsed : null;
+            }
+            catch (JsonException)
+            {
+                return null;
+            }
+        }
+
+        public static string? SerializeForStorage(IReadOnlyList<WorkOrderAdditionalContactDto>? contacts)
+        {
+            var normalized = NormalizeList(contacts);
+            if (normalized.Count == 0)
+                return null;
+
+            var json = JsonSerializer.Serialize(normalized, JsonOptions);
+            if (json.Length > MaxSerializedLength)
+            {
+                throw new WorkOrderBoardValidationException(
+                    "InvalidValue",
+                    "additionalContacts must serialize to at most 4000 characters.");
+            }
+
+            return json;
+        }
+
+        public static string? SerializeForPatch(string? jsonValue)
+        {
+            if (string.IsNullOrWhiteSpace(jsonValue))
+                return null;
+
+            List<WorkOrderAdditionalContactDto>? parsed;
+            try
+            {
+                parsed = JsonSerializer.Deserialize<List<WorkOrderAdditionalContactDto>>(jsonValue.Trim(), JsonOptions);
+            }
+            catch (JsonException)
+            {
+                throw new WorkOrderBoardValidationException(
+                    "InvalidValue",
+                    "additionalContacts must be a JSON array of { name, phone, notes? }.");
+            }
+
+            return SerializeForStorage(parsed);
+        }
+
+        public static List<WorkOrderAdditionalContactDto> NormalizeList(IReadOnlyList<WorkOrderAdditionalContactDto>? contacts)
+        {
+            var normalized = new List<WorkOrderAdditionalContactDto>();
+            if (contacts == null || contacts.Count == 0)
+                return normalized;
+
+            foreach (var raw in contacts)
+            {
+                var name = raw.Name?.Trim() ?? "";
+                var phone = raw.Phone?.Trim() ?? "";
+                var notes = raw.Notes?.Trim();
+
+                if (string.IsNullOrEmpty(name) && string.IsNullOrEmpty(phone))
+                    continue;
+
+                if (name.Length > MaxNameLength)
+                {
+                    throw new WorkOrderBoardValidationException(
+                        "InvalidValue",
+                        "Each additional contact name must be at most 200 characters.");
+                }
+
+                if (phone.Length > MaxPhoneLength)
+                {
+                    throw new WorkOrderBoardValidationException(
+                        "InvalidValue",
+                        "Each additional contact phone must be at most 50 characters.");
+                }
+
+                if (notes != null && notes.Length > MaxNotesLength)
+                {
+                    throw new WorkOrderBoardValidationException(
+                        "InvalidValue",
+                        "Each additional contact notes must be at most 2000 characters.");
+                }
+
+                normalized.Add(new WorkOrderAdditionalContactDto(
+                    name,
+                    phone,
+                    string.IsNullOrEmpty(notes) ? null : notes));
+            }
+
+            return normalized;
+        }
+    }
+}
diff --git a/SeaHaven.Services/Helpers/WorkOrderBoardFieldNames.cs b/SeaHaven.Services/Helpers/WorkOrderBoardFieldNames.cs
index 97f7744..45ae58f 100644
--- a/SeaHaven.Services/Helpers/WorkOrderBoardFieldNames.cs
+++ b/SeaHaven.Services/Helpers/WorkOrderBoardFieldNames.cs
@@ -19,6 +19,7 @@ namespace SeaHaven.Services.Helpers
         public const string Pm = "pm";
         public const string ServiceNotes = "serviceNotes";
         public const string ExtraServices = "extraServices";
+        public const string AdditionalContacts = "additionalContacts";
         public const string FlagColor = "flagColor";
         public const string RescheduleCount = "RescheduleCount";
 
@@ -48,6 +49,7 @@ namespace SeaHaven.Services.Helpers
             Pm,
             ServiceNotes,
             ExtraServices,
+            AdditionalContacts,
             FlagColor
         };
 
@@ -89,6 +91,7 @@ namespace SeaHaven.Services.Helpers
                 Pm => "Trade",
                 ServiceNotes => "ServiceNotes",
                 ExtraServices => "ExtraServices",
+                AdditionalContacts => "AdditionalContacts",
                 FlagColor => "FlagColor",
                 _ => canonical
             };
diff --git a/SeaHaven.Services/Implementation/WorkOrderBoardCreateService.cs b/SeaHaven.Services/Implementation/WorkOrderBoardCreateService.cs
index ee32e53..593b67b 100644
--- a/SeaHaven.Services/Implementation/WorkOrderBoardCreateService.cs
+++ b/SeaHaven.Services/Implementation/WorkOrderBoardCreateService.cs
@@ -59,6 +59,7 @@ namespace SeaHaven.Services.Implementation
             var pocName = TrimOrNull(request.PocName);
             var pocPhone = TrimOrNull(request.PocPhone);
             var pocNotes = TrimOrNull(request.PocNotes);
+            var additionalContactsJson = WorkOrderAdditionalContactsMapper.SerializeForStorage(request.AdditionalContacts);
             var techPhone = TrimOrNull(request.TechPhone);
             var vendorNotes = TrimOrNull(request.VendorNotes);
             var customer = TrimOrNull(request.Customer);
@@ -87,6 +88,7 @@ namespace SeaHaven.Services.Implementation
                 PocName = pocName,
                 PocPhone = pocPhone,
                 PocNotes = pocNotes,
+                AdditionalContacts = additionalContactsJson,
                 LocationId = request.LocationId,
                 DueDate = request.DueDate?.Date,
                 AssignTo = string.IsNullOrWhiteSpace(request.AssignTo) ? null : request.AssignTo.Trim(),
@@ -128,6 +130,8 @@ namespace SeaHaven.Services.Implementation
                 changes.Add(WorkOrderBoardFieldMutations.BoardFieldChange.Changed("PocPhone", "", workOrder.PocPhone));
             if (workOrder.PocNotes != null)
                 changes.Add(WorkOrderBoardFieldMutations.BoardFieldChange.Changed("PocNotes", "", workOrder.PocNotes));
+            if (workOrder.AdditionalContacts != null)
+                changes.Add(WorkOrderBoardFieldMutations.BoardFieldChange.Changed("AdditionalContacts", "", workOrder.AdditionalContacts));
             if (workOrder.TechPhone != null)
                 changes.Add(WorkOrderBoardFieldMutations.BoardFieldChange.Changed("TechPhone", "", workOrder.TechPhone));
             if (workOrder.VendorNotes != null)
diff --git a/SeaHaven.Services/Implementation/WorkOrderBoardService.cs b/SeaHaven.Services/Implementation/WorkOrderBoardService.cs
index 04bf63c..50d4261 100644
--- a/SeaHaven.Services/Implementation/WorkOrderBoardService.cs
+++ b/SeaHaven.Services/Implementation/WorkOrderBoardService.cs
@@ -121,6 +121,7 @@ namespace SeaHaven.Services.Implementation
                 Pm = row.Trade ?? row.Problem,
                 ServiceNotes = row.ServiceNotes,
                 ExtraServices = ParseExtraServices(row.ExtraServices),
+                AdditionalContacts = WorkOrderAdditionalContactsMapper.ParseJson(row.AdditionalContacts),
                 DocStatus = row.DocStatus,
                 CompletedDate = row.CompletedDate,
                 FlagColor = row.FlagColor,
diff --git a/SeaHaven.Services/Implementation/WorkOrderBoardUpdateService.cs b/SeaHaven.Services/Implementation/WorkOrderBoardUpdateService.cs
index 3e8c108..5b737dc 100644
--- a/SeaHaven.Services/Implementation/WorkOrderBoardUpdateService.cs
+++ b/SeaHaven.Services/Implementation/WorkOrderBoardUpdateService.cs
@@ -157,6 +157,7 @@ namespace SeaHaven.Services.Implementation
                 WorkOrderBoardFieldNames.Pm => new List<FieldChange> { ApplyStringField(value, auditField, v => workOrder.Trade = v, () => workOrder.Trade) },
                 WorkOrderBoardFieldNames.ServiceNotes => new List<FieldChange> { ApplyServiceNotes(workOrder, value, auditField) },
                 WorkOrderBoardFieldNames.ExtraServices => new List<FieldChange> { ApplyExtraServices(workOrder, value, auditField) },
+                WorkOrderBoardFieldNames.AdditionalContacts => new List<FieldChange> { ApplyAdditionalContacts(workOrder, value, auditField) },
                 WorkOrderBoardFieldNames.FlagColor => new List<FieldChange> { ApplyFlagColor(workOrder, value, auditField) },
                 _ => throw new WorkOrderBoardValidationException("InvalidField", $"Field '{field}' is not editable.")
             };
@@ -321,6 +322,18 @@ namespace SeaHaven.Services.Implementation
             return FieldChange.ForField(auditField, old, normalizedJson);
         }
 
+        private static FieldChange ApplyAdditionalContacts(WorkOrder workOrder, string? value, string auditField)
+        {
+            var normalizedJson = WorkOrderAdditionalContactsMapper.SerializeForPatch(value);
+
+            var old = workOrder.AdditionalContacts;
+            if (old == normalizedJson)
+                return FieldChange.Unchanged(auditField);
+
+            workOrder.AdditionalContacts = normalizedJson;
+            return FieldChange.ForField(auditField, old, normalizedJson);
+        }
+
         private static List<string> NormalizeExtraServiceList(List<string>? extras)
         {
             var normalized = new List<string>();
diff --git a/SeaHaven.Services/Validation/WorkOrderBoardCreateValidation.cs b/SeaHaven.Services/Validation/WorkOrderBoardCreateValidation.cs
index 8d0564d..48842c7 100644
--- a/SeaHaven.Services/Validation/WorkOrderBoardCreateValidation.cs
+++ b/SeaHaven.Services/Validation/WorkOrderBoardCreateValidation.cs
@@ -78,6 +78,24 @@ namespace SeaHaven.Services.Validation
             RuleForEach(x => x.ExtraServices)
                 .MaximumLength(128)
                 .When(x => x.ExtraServices != null);
+
+            RuleForEach(x => x.AdditionalContacts)
+                .ChildRules(contact =>
+                {
+                    contact.RuleFor(c => c.Name)
+                        .MaximumLength(200)
+                        .When(c => !string.IsNullOrEmpty(c.Name));
+                    contact.RuleFor(c => c.Phone)
+                        .MaximumLength(50)
+                        .When(c => !string.IsNullOrEmpty(c.Phone));
+                    contact.RuleFor(c => c.Notes)
+                        .MaximumLength(2000)
+                        .When(c => !string.IsNullOrEmpty(c.Notes));
+                    contact.RuleFor(c => c)
+                        .Must(c => !string.IsNullOrWhiteSpace(c.Name) || !string.IsNullOrWhiteSpace(c.Phone))
+                        .WithMessage("Each additional contact must include a name or phone.");
+                })
+                .When(x => x.AdditionalContacts != null);
         }
 
         private static bool HasPrimaryWhenExtras(WorkOrderBoardCreateRequestDto request)
diff --git a/SeaHavenIndustries.Tests/WorkOrderBoardCreateServiceTests.cs b/SeaHavenIndustries.Tests/WorkOrderBoardCreateServiceTests.cs
index bd5f2bf..7bc43da 100644
--- a/SeaHavenIndustries.Tests/WorkOrderBoardCreateServiceTests.cs
+++ b/SeaHavenIndustries.Tests/WorkOrderBoardCreateServiceTests.cs
@@ -4,7 +4,9 @@ using Microsoft.EntityFrameworkCore;
 using SeaHaven.DataServices.Implementation;
 using SeaHaven.Services.DTOs;
 using SeaHaven.Services.Exceptions;
+using SeaHaven.Services.Helpers;
 using SeaHaven.Services.Implementation;
+using SeaHaven.Services.Interfaces;
 using SeaHaven.Services.Validation;
 
 namespace SeaHavenIndustries.Tests;
@@ -351,4 +353,34 @@ public class WorkOrderBoardCreateServiceTests
 
         Assert.Equal("VendorNotFound", ex.Code);
     }
+
+    [Fact]
+    public async Task Create_AdditionalContacts_PersistsAndReturnsOnBoardRow()
+    {
+        var (context, service) = CreateSut();
+
+        var result = await service.CreateAsync(new WorkOrderBoardCreateRequestDto
+        {
+            WorkOrderType = WorkOrderType.Reactive,
+            SiteCode = "BK5",
+            PocName = "Primary Lead",
+            AdditionalContacts = new List<WorkOrderAdditionalContactDto>
+            {
+                new("Backup Lead", "+1 555-0101", "After hours"),
+                new("Security Desk", "+1 555-0102", null)
+            }
+        }, WorkOrderAccountTestHelpers.AccountUser(), "actor-1");
+
+        Assert.Equal("Primary Lead", result.PocName);
+        Assert.NotNull(result.AdditionalContacts);
+        Assert.Equal(2, result.AdditionalContacts!.Count);
+        Assert.Equal("Backup Lead", result.AdditionalContacts[0].Name);
+        Assert.Equal("+1 555-0101", result.AdditionalContacts[0].Phone);
+        Assert.Equal("After hours", result.AdditionalContacts[0].Notes);
+
+        var wo = await context.workOrders.SingleAsync(w => w.Id == result.Id);
+        Assert.NotNull(wo.AdditionalContacts);
+        Assert.Contains("Backup Lead", wo.AdditionalContacts);
+        Assert.Contains("Security Desk", wo.AdditionalContacts);
+    }
 }
diff --git a/SeaHavenIndustries.Tests/WorkOrderBoardUpdateServiceTests.cs b/SeaHavenIndustries.Tests/WorkOrderBoardUpdateServiceTests.cs
index b775ee6..f7705bf 100644
--- a/SeaHavenIndustries.Tests/WorkOrderBoardUpdateServiceTests.cs
+++ b/SeaHavenIndustries.Tests/WorkOrderBoardUpdateServiceTests.cs
@@ -354,6 +354,56 @@ public class WorkOrderBoardUpdateServiceTests
         Assert.Equal("InvalidValue", ex.Code);
     }
 
+    [Fact]
+    public async Task PatchField_UpdatesAdditionalContacts()
+    {
+        var (context, service) = CreateSut();
+        var wo = new WorkOrder
+        {
+            Id = 1,
+            LifecycleStatus = LifecycleStatus.Incomplete,
+            RowVersion = new byte[] { 1, 0, 0, 0, 0, 0, 0, 1 }
+        };
+        context.workOrders.Add(wo);
+        await context.SaveChangesAsync();
+
+        var result = await service.PatchFieldAsync(1, new WorkOrderBoardPatchRequestDto
+        {
+            Field = WorkOrderBoardFieldNames.AdditionalContacts,
+            Value = "[{\"name\":\"Jane Backup\",\"phone\":\"+1 555-0101\",\"notes\":\"Call first\"}]",
+            WorkOrderVersion = ToVersion(wo)
+        }, "actor-1");
+
+        Assert.NotNull(result.AdditionalContacts);
+        Assert.Single(result.AdditionalContacts!);
+        Assert.Equal("Jane Backup", result.AdditionalContacts![0].Name);
+        Assert.Contains("Jane Backup", (await context.workOrders.FindAsync(1))!.AdditionalContacts);
+    }
+
+    [Fact]
+    public async Task PatchField_InvalidAdditionalContactsJson_Throws()
+    {
+        var (context, service) = CreateSut();
+        var wo = new WorkOrder
+        {
+            Id = 1,
+            LifecycleStatus = LifecycleStatus.Incomplete,
+            RowVersion = new byte[] { 1, 0, 0, 0, 0, 0, 0, 1 }
+        };
+        context.workOrders.Add(wo);
+        await context.SaveChangesAsync();
+
+        var ex = await Assert.ThrowsAsync<WorkOrderBoardValidationException>(() =>
+            service.PatchFieldAsync(1, new WorkOrderBoardPatchRequestDto
+            {
+                Field = WorkOrderBoardFieldNames.AdditionalContacts,
+                Value = "not-json",
+                WorkOrderVersion = ToVersion(wo)
+            }, "actor-1"));
+
+        Assert.Equal("InvalidValue", ex.Code);
+    }
+
     [Fact]
     public async Task PatchField_SetsFlagColor_CanonicalUppercase()
     {