Alright, so I have:

Sisse Thompsett who is her cousin Calla's friend. Sisse would befriend her without a second thought if only because it's in her nature. But she'll also be friendly because of Calla. Annd she is often in the library or under a tree studying. We also discussed that Sisse might help hem some hand me gowns down to Millie, which I'll add to that that Sisse has the vague notion of either getting married or becoming a modieste after she graduates. Sisse is also the president of the Charms club and is in the history club. She has previously been in the book club - I think.

Katherine Arundell "Kitty" is the daughter of an earl and is a muggleborn first year. She is way out of her depth here at Hogwarts but pretty open talking to everyone. I definitely think we can find a way to put the two of them together.

@"Dahlia Potts" and of course, I have her next oldest cousin after Calla. Dahlia would definitely take Millie under her wing. She's an avid letter writer, very cheerful, and is probably the family gossip. She also tends to jump to conclusions and gets herself into some hilariously misunderstood situations. She loves baking and is really into being a debutante.