Federated graph resolve embedded document using mongodb

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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?