@Jobrien - from your own perspective, document everything up to now - take photos of the front & back etc, include timelines and as much info as you can in your notes.
Idealy, if you feeel up to it, talk to them again on this, but if you feel threatend or itimidated, etc, then just walk away and try not to get into a discussion / argument with them. It's a very stressful time on it's own, but with you brother's situation, we can only imagine how difficult this is