I think when first contact happens between loved ones, a common reality is unconsciously agreed upon where the family comes together under the bodies they inhabited at the time they were all together.

Since the long deceased ones have likely watched the life of the newly deceased with interest, I think that initial reality is then slowly pushed away and the (grown) children take on their more mature forms and the grand parents take on their younger forms, and they all walk away from the meeting as equals

That's how I'd do it

Don't worry. This isn't real. It's a painting or ai made from someone's imagination.

Bodies don't go to heaven. They decompose and become one with the earth.