Unexpected friend requests,…

I got a friend request on FaceBook this morning and I really don’t have a clue what to do about it.  The request came from someone I haven’t seen since she was in single digits, and she happens to be the youngest sister of an ex.  An ex that treated me horribly and we did not divorce on good terms.  We did manage to be almost friendly for a little while, but that was over 9½ years ago AND because he wanted something from me.  Needless to say, the friendliness was shortlived and I haven’t heard from him since, despite the fact that we have a child together.  And then, a few days ago, the ex started popping up with frightening frequency on my friend suggestions thing and I don’t know why or how that happened, since we have ZERO mutual friends.  And now his sister has friended me.  I guess the big question is why?  Both why is he suddenly popping up on my FaceBook suggestions AND why is his sister trying to friend me?  I can’t imagine that she remembers me, although obviously she must know who I am.  The last time I heard from any part of his family was about 7 or 8 years ago when his stepmother contacted me in Virginia.  And that wasn’t about my child, either.  That was to get a deposition against the ex in their attempt to gain custody of his daughter from him.  And now this, so I am more than a little curious as to why and what prompted it.  Of course, it could be she is completely innocent.  I wonder how she even found me on here, unless the ex actually remembers my maiden name.  Weird.