Here are a couple of threads from last year..... The advice is still good..check with the airlines for which you have points.
Currently there are no airline partnerships that allow air miles to be transferred to Marriott Rewards points. If you are short points for your upcoming stay, you always have the option of buying additional points. There is also the option to transfer points from a spouse or friend's account. Visit https://www.marriott.com/rewards/usepoints/tranpurc.mi to find out all of the details.