Simple rules of bidirectional relationships:
1.For many-to-one bidirectional relationships, the many side is always the owning side of the relationship. Example: 1 Room has many Person (a Person belongs one Room only) -> owning side is Person
2.For one-to-one bidirectional relationships, the owning side corresponds to the side that contains the corresponding foreign key.
3.For many-to-many bidirectional relationships, either side may be the owning side.
Hope can help you.