All explained here:
https://www.fimfiction.net/blog/758204/update-to-stallionverse-and-mgs-too-i-guess

Nuff said, expect a summary of next story in near future.

6090051
In that case could you please tell us what role King Blueblood would've played in the series and why he was Unpersoned?

6092933
There's wasn't much of a story when I first mentioned it, as it was something I was going to fill in later. I don't have a full story for it yet, but it was going to be King Sombra. You can imagine why your family doesn't wish to remember that name and why they changed it to Bluebloods.