Store relation with the parent entity in the database instead of the State API

Problem/Motivation

Currently the State API → is used to store the relationship between an entity and the parent entity it is inheriting from. The State API is not a permanent data store and is environment specific, so these relations are lost when moving data between environments.

We should instead use a permanent data store. Maybe a good candidate would be to store the relationship in a base field that is altered in on the child entity?