Celestia: Yes, they were mortal, either being their fathers tribe or our birth tribe. We dont even know if its possible for a foal to be born as an alicorn. It was hard, to say the least, when they passed. It was harder still when our grandchildren passed. I think we started to become more comfortable, though, with the natural order of life, even if we seem to be exempt from it.
As for our descendants, yes, Ive kept track of them, though we have no interaction. As far as they know, theyre normal ponies. There arent nearly as many as youd think, given the time. Maybe 100 at most. And no, neither Twilight nor Cadance are among them.
Luna: Twilight is aware. She was there when my sister and I had a trip down memory lane. This was well before we were together so she knew before she ever agreed to a date. She just looked very, very uncomfortable with the whole situation
Stupid long text. I have no idea how to portray all that headcanon in picture form. I also may be shooting myself in the foot depending on how Cadances kid comes out.