The Deep End of the Ocean
A kid of three years old is kidnapped; he will be retrieved after nine years. All of them will face difficult challenges, the parents, the boy, the adoptive father (who was rising the kid in good faith, without being aware of what had happened long time ago).
This is The Deep End of the Ocean, made in 1999, based on the best-seller of Jacquelyn Mitchard. I didn't have the chance to read the book; some say it is superior to the movie (which would not come as a surprise). What impressed me was the outcome of the story, treated with great sensibility and poignancy.
It called in my mind another movie, An American Rhapsody, as both of them offer somehow the same solution. The best decision can be taken only by the kid, if they let him find the answers in his own terms. And his decision will be of unexpected maturity: he will realize his importance and his responsibilities for the well being of the whole family.