Foster (2011)

Some years after their son is killed in an accident, a married couple decide to adopt a child. One day a 7-year-old boy, Eli, unexpectedly arrives on their doorstep claiming to be from the adoption agency. Eli wears a suit every day and is very well-spoken for a child. He helps the adults to process their loss, which had stifled both their marriage and their toy business, and lets them embrace life again.