If the transition is smoothe, I hope the father is psychologically mature enough to include “Aunt and Uncle” [the parents wanting to adopt his child] in their lives. Occasional visits, photos, cards and gifts.
He could ask them to be his daughter’s Godparents!
I would have advised him to end all contact with them.
there is no reason for any continued contact.
Their contact with the girl ended when the court ruled on the fraud which placed the child there.