Is there a way to query all child and grandchild documents by using the parent/grandparentID?

[Prasanth_Rajendran]

I have a below scenario: I am creating index called company where I am creating multilevel relationship

         company
            |
    |---------------|
department       supplier
    |
employee

I have created below mapping:

PUT /company
{
  "mappings": {
    "_doc":{
      "properties":{
        "join_field":{
          "type":"join",
          "relations":{
            "company": ["supplier", "department"],
            "department": "employee"
          }
        }
      }
    }
  }
}

I am able to query all the departments under company using the parent id (company id)

GET /company/_doc/_search
{
    "query":{
      "parent_id":{
        "type":"department",
        "id":1
      }
    }
}

I am able to query all the employees under the department of the company

GET /company/_doc/_search?routing=1
{
  "query":{
    "has_parent":{
      "parent_type":"department",
      "query":{
        "term":{
          "name.keyword":"Development"
        }
      }
    }
  }
}

finally, my question is, how to query all the department and employees of a company in a single query instead of fetching all departments and use those departments to fetch the employees? NOTE: I am using elastic search 7+ version