The thought that several nobles would witness the birth squicks me a bit, but I love it. The kid was born after the third season, right?

Well, I would say that Bella survived the second war, but died few years later in Azkaban, and that this story happened several years after the war.

Or that Zuko was sent to Iroh afterwards and kept those years in a different country, away from England and all the troubles there, then Iroh comes back to help at the rebuilding, or something like that.