Right. Jennifer and all of them should not be there in Hilldale as soon as Biff left and went back. How he came back to the same timeline but they don't is confusing.
Tell you what…When I send my ex-wife her money…you can lick the stamps.
The ripple effect. The changes in the now altered 2015 would happen gradually, like Marty's siblings in the photo. It's an established "rule" in the BTTF franchise.
Hey, it's a kind of magic!