Yeah, I understand that it sound stupid helping him fixing a fake ID by photoshopping his passport copy, but I thought that that was waterproof... Thought that in case of a police raid, they would only check the copy to see the birth date, but if they have some way to see if passport copys are valid, then it's not such a bright idea.
But you're right, forging a passport sound pretty serious if you would get caught...
But I know my brother and I know he will just borrow an ID from an friend (who is 20) if I don't help him.
Do you think I should try to talk him out from using a borrowed ID in Thailand as well and say that it's simply just the best to take the low consequences if getting caught by police as minor in Thailand, and that he doesnt wanna end up getting caught with a fake ID as that is far more severe.