I think your Kenobi idea has more merit than my Phasma one.
But making Rey Obi-Wan's granddaughter seems like a whole lot of hassle. I mean, you have to explain two stories there, right?
1.) Where and when did Obi-Wan - consistently portrayed as a sober and dutiful member of the Jedi Order - father a child, completely out of character? If Rey is 20, and her parents were at least 20 when she was born, that means that Ben's kid would have been born while he was watching over Luke on Tatooine. Would Obi-Wan really have distracted himself from his all-important mission by having a kid (or putting himself in a position where he accidentally had one)?
2.) Why did that kid leave their kid (Rey) with a greedy lout on some jerkwater planet? Again, if I am tracking the timeline right, when Rey got dumped, everything was still generally hunky-dory with the New Republic and the Jedi Order. No need to secret away a Force-sensitive child at that time, was there?
Again, I think you guys are right. I just question all the fiery hoops that Kasdan and Abrams jump through from a screenwriting standpoint to unnecessarily tie Rey back to Obi-Wan. Why can't she just be a brand-new powerful Force-wielder with no connection to anyone?