A friend of mine had the same problem with his son and adopted daughter; he was cruel to her for years. One year while at Disney, his son was being extra cruel and bold.
In front of his son, my friend told his adopted daughter that she should not be upset, that they didn’t have a choice with their son, but they chose her, and were happy they did. He also said the only reason his son was at Disney was that he was too young to leave home, and no one would watch him. The son ended up crying for two days. Even though his son was upset, my friend continued to give his daughter a lot more obvious attention. After about a week, my friend sat his son down to discuss how the boy felt.
That was 27 years ago. His son never said anything about his sister not being real family again and they’ve gotten along fantastically ever since. Fifteen years ago, the son adopted a lovely brother and sister, adding to his own family.
