Pleasure Slaves (Alien Ecstasy #4)
S.L. Hadley

Heather and her stepbrother, Aaron, have come to terms with their new, post-alien-abduction life. They're turned on all the time and can't satisfy themselves anymore.
Big deal. Next?
Now that they've connected with a group of fellow abductees, they're faced with another dilemma. Their new friends have some very... flexible ideas of monogamy. And as much as Heather and Aaron desire one another... they may not have that option for long.
It's almost time to share.