As a favour to you I will respond to this right now as you say it's only an alt you loaned to someone that griefed.
This being said I need you to understand that whether or not someone was using your alt, you are still responsible for everything that happens on it.
Please answer the following questions (Either yourself or your cousin, I don't mind who):
1. Why is taking blocks from a build that's not yours wrong?
2. Why is loaning an alt account to someone else still your responsibility?
3. What have you/your cousin learned from this?
This being said I need you to understand that whether or not someone was using your alt, you are still responsible for everything that happens on it.
Please answer the following questions (Either yourself or your cousin, I don't mind who):
1. Why is taking blocks from a build that's not yours wrong?
2. Why is loaning an alt account to someone else still your responsibility?
3. What have you/your cousin learned from this?
“Never be cruel, never be cowardly, and never ever eat pears!”
“Always try to be nice but never fail to be kind!”
“Laugh hard, run fast, be kind... “