We are SSR owners, and had studio ressies at SSR from 12/31 - 1/5. On May 2nd, we moved the first two nights to OKW. Two weeks later, on a lark, we called MS to inquire about BCV and VWL. Rooms were available, so the next day we called back and moved the 1/2-1/3 ressie to BCV, and the 1/4 ressie to VWL.
No problem - all within the seven month window!