Conveniently An Orphan has these relationships to other tropes:

parents kids shares a parent with:
Parental Abandonment
parent child
Parental AbandonmentBlitz Evacuees
''Missing Mom
''Disappeared Dad
''Deceased Parents Are The Best
''Promotion To Parent
''Death By Childbirth
''Bonding Over Missing Parents
You'll need to Get Known if you want to add or modify these relationships.