No, this is not possible. If you want to retrieve parents together with their child records, you can use the parent as base relation and join the child relation with its attributes.
Then you will get multiple lines for a parent (if it has multiple children), but get all desired details within the parent context. You can also use 2 APIs, one for parent and the other for the children. Then you do not have data duplication and would use keys to identify parent <-> child relationships.
