Good luck lol!
Edit: I would suggest the following to increase your chances
Have both Mom and Sis logged on ready to go on the dot. By the time you can call, the window has been open for online booking for an hour, and that's if you're first to be answered. Chances by then are slim to none.
Both should be trying to grab a studio, even if you are all planning to share one. You can always cancel one of them, and make someone else happy
Grab what you can, you can always phone Member Services to link odd nights together.
If you were logged on to get 31st Dec and it's gone. IMMEDIATELY go and waitlist it, just the one night. Quick and simplified explanation of waitlist follows
- you can have 2 waitlists going
- best to waitlist a single night on each
- if you have waitlisted both 31st and 1st in one request, both nights need to be available before yours will match. If Amy waitlists only the 31st a few days later, and the 31st becomes free, Amy will jump over you because that's all she wants.