I'm considering converting Marriott points to American Airlines points (20% bonus until 10/31/15) via a travel package with a CAT 1-5 7-night stay. A popular travel blogger made the following statement "You can later up the hotel award category by paying the difference in Marriott Rewards points". I have not found any evidence of this being possible and I haven't heard back from the blogger :-)
Can anyone confirm this is possible? If possible, how did you do it?