Nah

It's not so much "more backstory" as stuff that's graduated to the status of "general consensus." If you look at a lot of the earlier chapters in YAWYW, these things are quite a bit more up in the air, but as time went on people kind of settled into a de facto set of answers on these questions. Even now, there are things that aren't "standard" - is Jon's last name Madison, or Gibson? Sometimes Jon also has a dad in the picture? What's Jon's grandfather's name? All depends on who's telling.