1) You do not have to always call CRO.
2) The local Front Desk or Concierge desk can help you.
3) They can search for open rooms for your resort choice and dates.
4) Then, it can be determined right then if you can switch.
. . . the next resort can accept your transfer
. . . if you have a package, it is up the the new resort to honor it or not
. . . worst case is you pay rack rate for open rooms
NOTE: This happens more than you could guess. The process is straight forward. The only thing that upsets guests is when the next resort will not honor a room discount or package discount. However, if the next resort is close to full, why should they give away revenue. After all, each resort manager is responsible for profits at his/her resort.