I was a bit disappointed that today i was told by MS that i could not use the new feature to modify one day of a 4 day reservation to a diff resort.. i had 4 nights at BCV studio from Dec 26-30th and saw today that a BLT lake view studio showed up for my last night of Dec 29th.. so I went to modify my reservation for just that one night but was scared to continue b/c it seemed to look like it would remove ALL 4 nights at BCV and just replace with the one night at BLT. So called MS and they confirmed that I could not have just switched that one night using the tool, they did it the old fashioned way of releasing the one day and telling my how they may not be able to book the new night and I was at high risk of losing that night all together.. i decided to tell them to take the risk and release the one night and luckily i got the BLT night, but was very stressful! So if they gave me correct info, then it seems that you have to replace a whole reservation with a new one of at least the same length to work, not less.. does anyone else know if this is indeed the case?