Originally Posted by
sdsearch
Do you have a banking (checking / savings / CitiGold) relationship with Citi? People who do
can combine all cards under one login. People who don't generally
can't. Since you didn't mention whether you do or not, could it be that you do and
that's why you're able to do it?

My wife and I only have CC's with Citi, AA and non-AA cards, all are on one account for both of us.
edit: Looking at the wiki above, I have the listed Hilton card on the same account with both my AA platinums.