Morning Awaits (1983)

After years of trying to have a son, a couple finally decides to adopt one. While Shayne their only child is receptive at first, she finds herself getting increasingly jealous of Joel who has become the couple's center of attention. Shayne realizes that her adopted brother is no threat at all when he demonstrates his affection for her. But just when harmony is restored in the family, tragedy strikes during a beach excursion.