I remember some opps... My sim is still a YA so I think I'll go on Thanks, I'll use it!
Widonja, I hate to sink your boat but I think there was a consversation a while back saying that even if you don't use it as a unique opportunity, no Immortal can have it anyway.
So if you remember Immortal 1 completing opportunity A, they could have also completed opportunity B. If opportunity B is completed be someone else, whether or not it's a part of Immortal 1's 6 BlackOps, Immortal 1's immortality would be canceled out.
I wish I could find those quotes, because I know they said it better than I just did.