Three Plus Two has these relationships to other tropes:

parents kids shares a parent with:
Power Trio
Sixth Ranger
parent child
Power TrioFreudian Trio
''The Three Faces Of Eve
''The Hecate Sisters
''The Three Faces Of Adam
''Knight Knave And Squire
''Comic Trio
''Town Girls
''Land Sea Sky
''Three Successful Generations
Sixth RangerEleventh Hour Ranger
''Sixth Ranger Traitor
''Sailor Earth
You'll need to Get Known if you want to add or modify these relationships.