Heart and Souls.

A fateful night in 1959, four people die when the bus they are riding crashes. They continue as ghosts; their souls become eternally entwined to the life of a child born at the moment of their deaths as his guardians. Baby Thomas grows up to be a businessman who has memories of his playmates, but assumes they are products of his youthful imagination. When the ghosts realize they need Thomas' help to move on to the afterlife, they decide to make an appearance once more.