Ally likes people who like music and/or sing and dance. She's a shy 5th year Hufflepuff. So there can be things there.

Rapunzel is in the same year as Chidori and likes drawing; I imagine she's tried to talk to her before but respected her privacy if she wasn't into it.

I actually really want established CR with Kowalski and Jackie, but I'm not sure how positive it would be, so your call.