Green screen in a character into every movie, make them old in the original trilogy and younger in the prequels. They will be present for everything but no one acknowledges them. When anakin and padme frolick in AOTC, the character is there too. When Palpatine is shocking luke, hes just standing next to the emperor.
When vader is dying he is standing next to luke.
When we see all the ghosts at the end of ROTJ, he’s stood with them, but he’s not blue…he’s physically just standing there, blocking most of their vision.