register_not_agreed hook
 

What hook does the register_not_agreed error show up in?

Huh? I'm not sure what you mean. I can only find the phrase being used once. It's in the register.php file around line 178.

Right, but if I wanted to add another error conditions that would run in the same area, what php hook would I use?

How about the register_start hook?

I tried that and it instantly throws my error message when you click on the register button. I don't think it can be done the way I'd like without editing the php file, and that isn't gonna happen. I found a way around it, not how I wanted, but it will have to do, I guess.

Did you put a condition around it so it only acts with that one condition - do=addmember ?

Yes, I tried this:

This is what I have in the register_start hook right now that is working (thank to dp):

I wanted to throw my own new error message.