Here is my model:

type Cell {
  id: ID! @unique
  name: String!
  parent: Cell @relation(name: "CellsRelationship")
  children: [Cell!]! @relation(name: "CellsRelationship")
}

And here is what I obtain when I create two cells: 1) a first with no parent (root of the structure) 2) then another with the previously created cell defined as a parent:

{
        "id": "cjdswp3h40bnl0128th7xh704",
        "name": "Vision",
        "parent": null,
        "children": []
      },
      {
        "id": "cjdswzmjh0bwh0128tw6l18fv",
        "name": "Market Channels",
        "parent": {
          "name": "Vision"
        },
        "children": [
          {
            "id": "cjdswp3h40bnl0128th7xh704",
            "name": "Vision"
          }
        ]
      }