In terms of heirs marrying heirs, if Sansa married Willas Tyrell or he married Arianne Martell how would the inheritance of the mothers work? First son gets Highgarden while second gets mom’s, would a firstborn daughter get Dorne?

It’s a tricky situation, because we haven’t really seen the case of a house holding multiple holdfasts directly, and we’re told that there’s a tradition of not allowing that, and instead creating cadet branches.

My guess is that they’ll create cadet branches rather than trying to have the same family rule both locations.