Obviously, Katie is going to be totally BFF with them both.
Why do I want to be really evil and say that at some point she and Draco engaged in a heated snog that neither of them will EVER tell anyone else about?
Oh, right, because I am me.
IDK how likely either of them are to interact with Sophia. Soph was in Draco's year and she also works at the Ministry, so I am sure we could do something with either of those.