Originally Posted by BringBackTWA

This is not accurate in my experience. I have multiple Citi HHonors cards, multiple Citi AAdvantage personal cards, and a Citi ThankYou card all tied to the same online account. The way I do this is:
1. Activate a new card by phone or online (if online, do not create a new online account)
2. Log in to your main Citi personal account online
3. Click "Profile & Settings"
4. Click "Link/Unlink a Credit Card"
5. Under "Link Account: Enter Information" select "Credit Card" from the drop-down under "Account Type:"
6. Enter the "Credit Card Account Number" and click "Next", then follow any remaining prompts.

When looking at my main account view I can see point balances for my Citi ThankYou, HHonors, and AAdvantage accounts along the right-hand side.

It would drive me crazy to have separate online accounts for each Citi co-branded card type. If you currently do and want to combine them all, I'd recommend following the steps I list above until you get to #5, and "Unlink" cards from old accounts and link them to your new/main account.

I also have a CitiBusiness AAdvantage card and did need to create a separate account for that one, which I hated having to do.