Whistlekit and Sedgekit could be friends with them! Both are becoming a moon old next week, so their ages are close.
Whistlekit has more of a flow-with-the-wind personality, and could either be a bad influence, or a good one, depending on how you look at things. And she does have a mean streak, so it really depends on their dynamic. Sedgekit is more grounded, serious, and sweet, and has an older-brother-next-door vibe. I think they'll get along.