I tried to do a thing. It was a big thing. A complicated one. So big and complicated, in fact, that I couldn't do it all in one image with ease. Because of that, I decided to split it into four parts. Now, I give you...
THE SEKAIRO FAMILY TREE: PART 1: RAHN'DAR'S LEGACY
This part goes over the lesser known portion of the Sekairo family- the side descended from the older of the two Kairo brothers. He was a Sith who married a Jedi (ew, right?) and had three kids. Eventually he died, but not before taking the name of "Darth Se". Later on his brother, Eske'Dar, would change his name to Eske'Dar Sekairo, in honor of his brother. That's what started the whole big thing that lead to Ven and Ire.
Eske's side of the family started considering Rahn a sort of spiritual figure after several generations, his kids becoming legends of sorts. That eventually lead to the idea that Rahn's 'sons' (great-grandchildren) were the 'ideal' Sekairos. While their existence is questionable, they're still on this family tree because it's what the rest of the family believes is true.
Now, for a mini-guide on what the color coding means: A greyed out image means the person is dead (or assumed dead). A dark grey border indicates that the person was morally ambiguous, a red border means they were morally chaotic, and a blue border means that they were morally 'good' and whatnot.
Without further ado, here's the thing with the thing. It's in a spoiler because it's a damn big image.