diff --git a/src/SIL.Harmony/Adapters/CustomAdapterProvider.cs b/src/SIL.Harmony/Adapters/CustomAdapterProvider.cs
index 00b723eb..cbcbe64d 100644
--- a/src/SIL.Harmony/Adapters/CustomAdapterProvider.cs
+++ b/src/SIL.Harmony/Adapters/CustomAdapterProvider.cs
@@ -18,7 +18,7 @@ public CustomAdapterProvider(ObjectTypeListBuilder objectTypeListBuilder)
         _objectTypeListBuilder = objectTypeListBuilder;
         JsonTypes.AddDerivedType(typeof(IObjectBase), typeof(TCustomAdapter), TCustomAdapter.TypeName);
     }
-    
+
     public CustomAdapterProvider<TCommonInterface, TCustomAdapter> AddWithCustomPolymorphicMapping<T>(string typeName,
         Action<EntityTypeBuilder<T>>? configureEntry = null
     ) where T : class, TCommonInterface
@@ -28,7 +28,8 @@ public CustomAdapterProvider<TCommonInterface, TCustomAdapter> AddWithCustomPoly
     }
 
     public CustomAdapterProvider<TCommonInterface, TCustomAdapter> Add<T>(
-        Action<EntityTypeBuilder<T>>? configureEntry = null
+        Action<EntityTypeBuilder<T>>? configureEntry = null,
+        Action<JsonTypeInfo>? jsonTypeModifier = null
     ) where T : class, TCommonInterface
     {
         _objectTypeListBuilder.CheckFrozen();
@@ -39,7 +40,7 @@ public CustomAdapterProvider<TCommonInterface, TCustomAdapter> Add<T>(
                     var entity = builder.Entity<T>();
                     configureEntry?.Invoke(entity);
                     return entity;
-                })
+                }, jsonTypeModifier)
         );
         return this;
     }
@@ -69,4 +70,4 @@ public interface ICustomAdapter<TSelf, TCommonInterface> : IObjectBase, IPolyTyp
     public static abstract TSelf Create(TCommonInterface obj);
     static string IPolyType.TypeName => TSelf.AdapterTypeName;
     public static abstract string AdapterTypeName { get; }
-}
\ No newline at end of file
+}
diff --git a/src/SIL.Harmony/Adapters/IObjectAdapterProvider.cs b/src/SIL.Harmony/Adapters/IObjectAdapterProvider.cs
index 712223d8..7e993f31 100644
--- a/src/SIL.Harmony/Adapters/IObjectAdapterProvider.cs
+++ b/src/SIL.Harmony/Adapters/IObjectAdapterProvider.cs
@@ -1,13 +1,14 @@
+using System.Text.Json.Serialization.Metadata;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Metadata.Builders;
 
 namespace SIL.Harmony.Adapters;
 
-internal record AdapterRegistration(Type ObjectDbType, Func<ModelBuilder, EntityTypeBuilder> EntityBuilder);
+internal record AdapterRegistration(Type ObjectDbType, Func<ModelBuilder, EntityTypeBuilder> EntityBuilder, Action<JsonTypeInfo>? JsonTypeModifier = null);
 
 internal interface IObjectAdapterProvider
 {
     IEnumerable<AdapterRegistration> GetRegistrations();
     IObjectBase Adapt(object obj);
     bool CanAdapt(object obj);
-}
\ No newline at end of file
+}
diff --git a/src/SIL.Harmony/CrdtConfig.cs b/src/SIL.Harmony/CrdtConfig.cs
index 2ae08959..c96aa4df 100644
--- a/src/SIL.Harmony/CrdtConfig.cs
+++ b/src/SIL.Harmony/CrdtConfig.cs
@@ -69,6 +69,12 @@ private void JsonTypeModifier(JsonTypeInfo typeInfo)
                 typeInfo.PolymorphismOptions!.DerivedTypes.Add(type);
             }
         }
+
+        var registration = ObjectTypeListBuilder.RegistrationsByType.GetValueOrDefault(typeInfo.Type);
+        if (registration?.JsonTypeModifier is not null && registration.ObjectDbType == typeInfo.Type)
+        {
+            registration.JsonTypeModifier(typeInfo);
+        }
     }
 
     public bool RemoteResourcesEnabled { get; private set; }
@@ -131,6 +137,7 @@ public void Freeze()
     {
         if (_frozen) return;
         _frozen = true;
+        _frozenRegistrationsByType = RegistrationsByType;
         foreach (var registration in AdapterProviders.SelectMany(a => a.GetRegistrations()))
         {
             ModelConfigurations.Add((builder, config) =>
@@ -156,6 +163,10 @@ internal void CheckFrozen()
 
     internal List<IObjectAdapterProvider> AdapterProviders { get; } = [];
 
+    private IReadOnlyDictionary<Type, AdapterRegistration>? _frozenRegistrationsByType;
+    internal IReadOnlyDictionary<Type, AdapterRegistration> RegistrationsByType
+        => _frozenRegistrationsByType ?? AdapterProviders.SelectMany(p => p.GetRegistrations()).ToDictionary(r => r.ObjectDbType);
+
     public DefaultAdapterProvider DefaultAdapter()
     {
         CheckFrozen();
@@ -164,7 +175,7 @@ public DefaultAdapterProvider DefaultAdapter()
         AdapterProviders.Add(adapter);
         return adapter;
     }
-    
+
     /// <summary>
     /// add a custom adapter for a common interface
     /// this is required as CRDT objects must express their references and have an Id property