Yes it is. I did just that recently. We got some developer points with our recent add-on and modified existing reservations we made last year to use the developer points. Apparently, it is not the easiest thing to do and I had several MS cast members give a little "huff" when I asked them to do this, but it is possible. They told me they would make the note and and apparently there is another department or group that does those ressies. MS told me I would see the activity in about 72 hours.