Per the T&Cs found Buy, Transfer or Convert Points , you are only supposed to be able to transfer points from a spouse or SO's account for enough points to order the award you need.

Note that Marriott doesn't enforce the spouse or SO account, but lets virtually anyone to transfer to anyone's account the points needed for an award. I say that as I have, in the past, transfered points from my wife's account into mine even though I had the needed points. I can't say whether that was a one-time over site from Marriott's perspective. Or if it is like the spouse's account issue and Marriott doesn't enforce it.

So my answer is YMMV, but they could very well say no to your request. And they would be within their stated rules to do so.