I don't think triplet or twin names should have the same "first letters"
I like basing it on meanings instead.
I suggest
Robyn,
Roza, and
Zahra.
Robyn is English for "bright fame,
Roza is Ancient Germanic for "fame", and
Zahra is Arabic for "brilliant, bright".
My two favorite Ro- names are
Roxana and
Rosaleen (I personally like it better than
Rose).