diff --git a/lib/ash_phoenix.ex b/lib/ash_phoenix.ex
index 75d0a1f..7bcdef6 100644
--- a/lib/ash_phoenix.ex
+++ b/lib/ash_phoenix.ex
@@ -241,22 +241,15 @@ defmodule AshPhoenix do
     [^outer_form_name, key | path] = decode_path(path)
 
     {argument, argument_manages} =
-      if changeset.action do
-        {nil, nil}
+      with action when not is_nil(action) <- changeset.action,
+           argument when not is_nil(argument) <-
+             Enum.find(changeset.action.arguments, &(to_string(&1.name) == key)),
+           manage_change when not is_nil(manage_change) <-
+             find_manage_change(argument, changeset.action) do
+        {argument, manage_change}
       else
-        # This is some magic to avoid having to pass in the relationship name
-        # when we can figure it out from the action
-        argument =
-          changeset.action.arguments
-          |> Enum.find(&(to_string(&1.name) == key))
-
-        if argument do
-          manage_change = find_manage_change(argument, changeset.action)
-
-          if manage_change do
-            {argument, manage_change}
-          end
-        end
+        _ ->
+          {nil, nil}
       end
 
     changeset.resource
@@ -350,22 +343,15 @@ defmodule AshPhoenix do
     [^outer_form_name, key | path] = decode_path(path)
 
     {argument, argument_manages} =
-      if changeset.action do
-        {nil, nil}
+      with action when not is_nil(action) <- changeset.action,
+           argument when not is_nil(argument) <-
+             Enum.find(changeset.action.arguments, &(to_string(&1.name) == key)),
+           manage_change when not is_nil(manage_change) <-
+             find_manage_change(argument, changeset.action) do
+        {argument, manage_change}
       else
-        # This is some magic to avoid having to pass in the relationship name
-        # when we can figure it out from the action
-        argument =
-          changeset.action.arguments
-          |> Enum.find(&(to_string(&1.name) == key))
-
-        if argument do
-          manage_change = find_manage_change(argument, changeset.action)
-
-          if manage_change do
-            {argument, manage_change}
-          end
-        end
+        _ ->
+          {nil, nil}
       end
 
     changeset.resource
@@ -455,6 +441,8 @@ defmodule AshPhoenix do
                     {Map.update!(changeset.data, rel, &hide/1), nil}
                 end
             end
+          else
+            {changeset.data, []}
           end
 
         changeset = mark_removed(changeset, new_value, rel)
@@ -470,20 +458,15 @@ defmodule AshPhoenix do
   end
 
   defp find_manage_change(argument, action) do
-    Enum.find(action.changes, fn
-      {Ash.Resource.Change.ManageRelationship, opts} ->
-        opts[:argument] == argument.name
+    Enum.find_value(action.changes, fn
+      %{change: {Ash.Resource.Change.ManageRelationship, opts}} ->
+        if opts[:argument] == argument.name do
+          opts[:relationship]
+        end
 
       _ ->
-        false
-    end)
-    |> case do
-      nil ->
         nil
-
-      {_, opts} ->
-        opts[:relationship_name]
-    end
+    end)
   end
 
   @doc """
@@ -670,13 +653,21 @@ defmodule AshPhoenix do
   end
 
   defp add_to_path(nil, [], add) do
-    add
+    List.wrap(add)
   end
 
   defp add_to_path(value, [], add) when is_list(value) do
     value ++ List.wrap(add)
   end
 
+  defp add_to_path(value, [], add) when value == %{} do
+    [value] ++ List.wrap(add)
+  end
+
+  defp add_to_path(value, [key | rest], add) when is_integer(key) and value == %{} do
+    add_to_path([value], [key | rest], add)
+  end
+
   defp add_to_path(value, [key | rest], add) when is_integer(key) and is_list(value) do
     List.update_at(value, key, &add_to_path(&1, rest, add))
   end
@@ -706,6 +697,8 @@ defmodule AshPhoenix do
     %{key => add_to_path(nil, rest, add)}
   end
 
+  defp add_to_path(_, _, add), do: add
+
   defp remove_from_path(value, [key]) when is_integer(key) and is_list(value) do
     List.delete_at(value, key)
   end
@@ -754,7 +747,15 @@ defmodule AshPhoenix do
 
   defp remove_from_path(value, _), do: value
 
-  defp decode_path(path) do
+  @doc """
+  A utility for decoding the path of a form into a list.
+
+  For example:
+    change[posts][0][comments][1]
+    ["change", "posts", 0, "comments", 1]
+
+  """
+  def decode_path(path) do
     path = Plug.Conn.Query.decode(path)
     do_decode_path(path)
   end
diff --git a/lib/ash_phoenix/form_data/changeset.ex b/lib/ash_phoenix/form_data/changeset.ex
index 346e43c..10fe045 100644
--- a/lib/ash_phoenix/form_data/changeset.ex
+++ b/lib/ash_phoenix/form_data/changeset.ex
@@ -95,6 +95,13 @@ defimpl Phoenix.HTML.FormData, for: Ash.Changeset do
         rel = Ash.Resource.Info.relationship(changeset.resource, field) ->
           data = relationship_data(changeset, rel, use_data?, opts[:id] || rel.name)
 
+          data =
+            if rel.cardinality == :many && data do
+              List.wrap(data)
+            else
+              data
+            end
+
           {rel, rel.destination, data}
 
         attr = Ash.Resource.Info.attribute(changeset.resource, field) ->
@@ -171,11 +178,25 @@ defimpl Phoenix.HTML.FormData, for: Ash.Changeset do
           [] ->
             nil
 
-          data when is_list(data) ->
-            List.last(data)
-
           value ->
-            value
+            value =
+              if is_list(value) do
+                List.last(value)
+              else
+                value
+              end
+
+            if use_data? do
+              data = changeset_data(changeset, rel)
+
+              if data do
+                Ash.Changeset.new(data, value)
+              else
+                value
+              end
+            else
+              value
+            end
         end
     end
   end
@@ -190,10 +211,29 @@ defimpl Phoenix.HTML.FormData, for: Ash.Changeset do
         end
 
       {manage, _opts} ->
-        manage
+        if use_data? do
+          changeset
+          |> changeset_data(rel)
+          |> zip_changes(manage)
+        else
+          manage
+        end
     end
   end
 
+  defp zip_changes([], manage) do
+    manage
+  end
+
+  defp zip_changes([record | rest_data], [manage | rest_manage]) do
+    [Ash.Changeset.new(record, manage) |> Map.put(:params, manage)] ++
+      zip_changes(rest_data, rest_manage)
+  end
+
+  defp zip_changes(records, []) do
+    records
+  end
+
   defp get_managed(changeset, relationship_name, id) do
     manage = changeset.relationships[relationship_name] || []
 
diff --git a/lib/ash_phoenix/form_data/helpers.ex b/lib/ash_phoenix/form_data/helpers.ex
index fa5a8cc..66ea51d 100644
--- a/lib/ash_phoenix/form_data/helpers.ex
+++ b/lib/ash_phoenix/form_data/helpers.ex
@@ -61,7 +61,17 @@ defmodule AshPhoenix.FormData.Helpers do
           update_action = Ash.Resource.Info.primary_action(resource, :update)
 
           if update_action do
-            Ash.Changeset.for_update(data, update_action.name, %{})
+            accepted_relationships =
+              resource
+              |> accepted_relationships(update_action)
+              |> Enum.map(fn relationship ->
+                {relationship.name, {:manage, [meta: [id: relationship.name]]}}
+              end)
+
+            Ash.Changeset.for_update(data, update_action.name, %{},
+              relationships: accepted_relationships,
+              actor: opts[:actor]
+            )
           else
             Ash.Changeset.new(data)
           end
@@ -69,7 +79,17 @@ defmodule AshPhoenix.FormData.Helpers do
           create_action = Ash.Resource.Info.primary_action(resource, :create)
 
           if create_action do
-            Ash.Changeset.for_create(resource, create_action.name, data)
+            accepted_relationships =
+              resource
+              |> accepted_relationships(create_action)
+              |> Enum.map(fn relationship ->
+                {relationship.name, {:manage, [meta: [id: relationship.name]]}}
+              end)
+
+            Ash.Changeset.for_create(resource, create_action.name, data,
+              relationships: accepted_relationships,
+              actor: opts[:actor]
+            )
           else
             Ash.Changeset.new(resource, data)
           end
@@ -128,7 +148,17 @@ defmodule AshPhoenix.FormData.Helpers do
       cond do
         is_struct(data) ->
           if update_action do
-            Ash.Changeset.for_update(data, update_action.name, %{})
+            accepted_relationships =
+              resource
+              |> accepted_relationships(update_action)
+              |> Enum.map(fn relationship ->
+                {relationship.name, {:manage, [meta: [id: relationship.name]]}}
+              end)
+
+            Ash.Changeset.for_update(data, update_action.name, %{},
+              relationships: accepted_relationships,
+              actor: opts[:actor]
+            )
           else
             data
             |> Ash.Changeset.new()
@@ -140,7 +170,17 @@ defmodule AshPhoenix.FormData.Helpers do
 
         true ->
           if create_action do
-            Ash.Changeset.for_create(resource, create_action.name, data)
+            accepted_relationships =
+              resource
+              |> accepted_relationships(create_action)
+              |> Enum.map(fn relationship ->
+                {relationship.name, {:manage, [meta: [id: relationship.name]]}}
+              end)
+
+            Ash.Changeset.for_create(resource, create_action.name, data,
+              relationships: accepted_relationships,
+              actor: opts[:actor]
+            )
           else
             resource
             |> Ash.Changeset.new(data)
@@ -202,9 +242,9 @@ defmodule AshPhoenix.FormData.Helpers do
       data
       |> Enum.map(fn data ->
         if is_struct(data) do
-          Ash.Changeset.for_update(data, update_action, %{})
+          Ash.Changeset.for_update(data, update_action, %{}, actor: opts[:actor])
         else
-          Ash.Changeset.for_create(resource, create_action, data)
+          Ash.Changeset.for_create(resource, create_action, data, actor: opts[:actor])
         end
       end)
 
@@ -263,13 +303,13 @@ defmodule AshPhoenix.FormData.Helpers do
     changeset =
       cond do
         is_struct(data) ->
-          Ash.Changeset.for_update(data, update_action, %{})
+          Ash.Changeset.for_update(data, update_action, %{}, actor: opts[:actor])
 
         is_nil(data) ->
           nil
 
         true ->
-          Ash.Changeset.for_create(resource, create_action, data)
+          Ash.Changeset.for_create(resource, create_action, data, actor: opts[:actor])
       end
 
     if changeset do
@@ -303,4 +343,23 @@ defmodule AshPhoenix.FormData.Helpers do
       }
     end
   end
+
+  defp accepted_relationships(resource, action) do
+    accepted =
+      if action.accept do
+        resource
+        |> Ash.Resource.Info.relationships()
+        |> Enum.filter(&(&1.name in action.accept))
+      else
+        Ash.Resource.Info.relationships(resource)
+      end
+
+    if action.reject do
+      resource
+      |> Ash.Resource.Info.relationships()
+      |> Enum.reject(&(&1.name in action.reject))
+    else
+      accepted
+    end
+  end
 end