How to build federated reference for one to many

[FBurner]

I have a one to many relation but i found none how to build a proper reference for grapqhql federation in nestjs query.
Worked with the regular implementation in nestjs

@reference('publishing', () => PublishingReferenceEntity, { id: 'publishingIds' })

Mongoose reference:
@prop( [{type: Types.ObjectId}])
publishingIds!: Types.ObjectId[];

[FBurner]

Out side of my first question, i have a question to the Query Service

it says following:
RelationQueryService#
The first step is to create a RelationQueryService. The RelationQueryService is a special type of QueryService that allows looking up relations without defining them in your entity.

How should the relation no be defined in the entity does it mean i can manipulate relation with graphql from the outside and eventually can query any id?

Or does it mean i can nevery call subtasks from todo item via graphql so i alway got to go over subtasks, i cannot really make sense of it currently.