Federated graph resolve embedded document using mongodb

Hi, I’m using and Apollo federated graph with node and mongod. I have two services, each with their own database, and I’m trying to use a type from another service to resolve some embedded data. I know I can use __resolveReference in my service, but I have all the data embedded - I don’t need to look the item up - I just need to use the type and its field resolvers from my other service.

This is just an example of my problem, so if I have a “Box” collection in one database and an “Item” collection in the other, and when creating a “Box” I embed the “Item” data like this:

   "_id": "1234",
   "name": "Box",
   "contents": {
      "addedAt": "",
      "item": {
          "name": "item",
          "description": "desc"


And my types like this:

// Box service
type Box {
   id: ID!
   name: String!
   items: [BoxItem]

type BoxItem {
   addedAt: DateTime!
   Item: Item!

// Item service
type Item {
   id: ID!
   name: String!
   description: String
   createdAt: DateTime!
   expiresAt: DateTime!
   expiresInDays: String //<--- item field resolver that returns a human readable string of how many days to expiry date

What would be the best way for my federated graph to resolve the Item type that is embedded in my BoxItem type so I get all the typed fields and field resolvers?