Re: New Background in 6e Rulebook
The chart with the First Founding Chapters in the new book is exactly the same chart that's been used since 2nd Edition, with the exact same footnotes - so the Ultramarines Successors that it names are still the ones from the Apocrypha of Davio (you know, the one which says there are 23 but "fails to name them"). The important word you need to be focusing on here is "Apocrypha": that chart has always been intentionally inaccurate and subject to the ravages of time and Imperial bureaucratic incompetence. It's an in-universe source, not Word of God background.
Originally Posted by Veteran Sergeant
Like with the two missing Legions, it's there to give fans a bit of room to play with.