A sibling reference is a relationship from one record in a subject area to a child record within that subject area.
For a data model, a customer could include both address and phone number child records, with the phone number having a foreign key to associate it with a specific address. IDD can be configured to support this kind of relationship.
When adding or editing the address key on the phone number, the IDD application user is given a list of addresses that contains only children of this party.