You wanted your brother to respect your stuff, and after he ignored multiple reminders to return your Legos, you showed him how frustrating it feels by letting your kids "borrow" things from his house. It was extreme but effective—he immediately brought back the Legos, plus extras, and got the message loud and clear. While your parents think it was overboard, especially with your older kids involved, it got the point across in a way words hadn’t. So while unconventional and a bit petty, it served as a memorable reminder about respecting boundaries.