Ben has Skywalker blood and Rey takes on the name Skywalker.
ROTS: Put all the deleted scenes back in.
TFA: Snoke is Plagueis (just for the heck of it.)
Groan
TLJ: DJ stays with the good guys the whole time
At the point you pretty much have to rewrite his entire character including even his name (it’s short for Don’t Join).
TROS: New script
That’s not one change.