the way i re~imagine it, after yoda dies, ben takes luke aside and tells him “the other he spoke of is your twin sister…” i tried to keep as much of the original dialogue and story as possible so instead of luke saying “leia leia is my sister!!” it goes like this (in my pee brain!)
ben “to protect you both from the emperor you were hidden from your father when you were born…the emperor knew as i did that if anakin were to have any offspring they would be a threat to him…that is the reason your sister remains safely anonymous”
then luke would say something like “but where is she? how will i find her”
then ben says “the force will guide her destiny as it has guided yours…use your feelings and find her you will lol”
then luke could say in astonished joy “i have a sister…”
ben “bury your feelings deep down luke…they do you credit but they could be made to serve the empire!!”