arent them more related to the xmen anyway?
I mean, they are mutated/uplifted by the Kree.
How does that connect them to the X-Men? The alien race the X-Men have ahad the most contact with is the Shi'ar. You could say that because of the Kree/ Shi'ar War, that's the connection, but that is incredibly tenuous, at best. The only other Kree/ X-Men connection is Rogue/ Carol Danvers, and that's very long and complicated and makes my head hurt thinking about it.
EDIT: I just remembered that Crystal and Quicksilver were married and have a daughter. So there's that too.