There seems to be some conflict about the family connection of the Emersons in the two movies. Personally, I believe this to be the fault of the lacklustre rush-job that is the comic book tie-in. In Lost Boys: Reign of Frogs, it's made claim by Edgar Frog that both Star and Michael were killed in a car crash. When Chris and Nicole move to Luna Bay to live with their aunt, it's revealed that their parents met the same fate, which would lead us to believe that their parents are in fact Michael and Star.
However, Star and Michael are never actually named as being Chris and Nicole's parents in either the comics or the sequel. It's Warner Bros. who clear this up on the Boys: The Tribe Official Site:
He moves to Lunar Bay and tries to settle under the radar. He would have stayed hidden except that two of Sammy's cousins needed help in a bad, anti-blood sucking way.
So there you have it, in black and white. The only real confirmation either way and I think it's safe to say that for the sake of keeping things sane on this Wiki, this is how they should be listed. Cousins.
Thanks for reading, Head Vampire LC