Do you think the characters lived their lives all over again since birth, or does it start with alternate 815 ? I'd go for the second : for instance, Jack dies, boom, wakes up on alternate 815 with modified memories ( he looked confused, didn't he ? ). Evidence : the wounds sustained against the MIB are still visible. Are we really to think he carried those all his ( alternate ) life without noticing them ? But, but, why would his mom tell a story about an appendix operation to explain the side wound, since, if I'm right, the version of kid Jack she's talking about never existed, is a fake memory ? According to you, does that mean :
A. the appendix operation did occur in the FST, there has been a kid Jack in the FST, and the island, or whatever you want to name the force behind the FST, created this scenario to match his fatal wound, should it reemerge as it does during "Lighthouse" ? As I said, unlikely, since Jack would have noticed the scar before, but still a possibility.
B. Margo Shepard was implanted false memories like anybody else on the FST ? But why doesn't Jack have this fake memory of his operation too, then ?
C. That's not Margo speaking, but "something" has taken control of her to apease Jack's suspicions, to keep him in the FST. All right, I know the FST's point is to "move on", not be stuck in it, but by that point, Jack hadn't solved his daddy issues ... so he had to remain in the FST for now. Of course, I'm assuming Margo's the real deal, but maybe she's just, all along, an empty puppet for the "something" I'm talking about ...