1. Can you combine 2 Citibank cards? (Platinum Select and Reg. AAdvantage) 2. Do they have to be at least 6 months old? 3. Can you upgrade Reg. AAdvantage to Gold AADvantage? (I know you can upgrade Reg. AAdvantage to Platinum Select card) 4. How often do they give credit increases without asking for them? If you know the answers to any of these questions please feel free to answer, but if you do answer, say how you know i.e did a rep tell you or did this personally happen to you. Thank you.