Hi! I'm Erin M., a d I have two girls, and both have ties to Celia!
Primrose Dursley (primlyrose) was a Hufflepuff 1994-2001. She was shy and awkward around pretty much everyone unless they managed to gently work their way under her defences. She was (and is) kind to the point of doormat because she wants to be liked, so that means being pleasant. She will be kind to Celia, but I think she can only handle her in small doses. Though, maybe the six months since the finished school has done the whole "absence makes the heart fonder" thing, and Prim will surprise us. (in other words, she could use friends outside of her family).
Then there's Ginny Weasley who played with Celia at school, was her captain for the 98-99 school year, and worked with her to get her to become captain. They can comiserate over their status of the youngest of a brood, and though Ginny plays the "older and wiser" card (she says that one year and three months makes all the difference), it's just a joke. They are friends, so there!