There is a lot of information here so bare with me. I know this process well not from working there, but I just returned from WDW under a cast member reservation.
To start - I'm sure she knows this, but the original booking has to be done through her portal to get the discount. Once that is made, you can change rooms and discount rates (so long as better ones are available) by simply calling Disney like you would with a normal reservation. Let them know you're booked under your daughter and that you're looking at other resorts and they can play with the numbers and rooms that will be available. I would book it ASAP for a Nov/Dec reservation because there are a limited number of discounted rooms available. The sooner you book the more options you have in terms of different resorts and discount rates.
For example:
If you book now you may able to get a room at Port Orleans Riverside for 50% off, but if you wait another month, there may only be rooms with a 30% discount available.
Now that you got that, the rates when we went, which will be the discount rates when you go are as follows:
30-50% if she IS NOT staying in the room with you
60% if she IS staying in the room with you
A couple things to consider:
- She will have to bring her ID to the hotel and check you in within 10 days of your arrival date no matter which option you choose
- They don't "check" to see if she is staying with you - but I wouldn't risk it for a hundred or so dollars in the discount difference between 50 and 60%.
- Almost every single room type in essentially every hotel had a 50% discount rate. We had no trouble with that. Interestingly, when our room was originally booked the CM who booked it couldn't find any rooms with better than a 40% discount. As soon as we got off the phone with her, I called Disney and asked about a better discount and instantly found tons of rooms with the 50% off rate in almost every hotel.
Lastly,
Cast members get extra discounts during the holiday (Christmas) season. She may be able to get you a better discount than 50% without her in the room and 60% with her in it. She will also get tons of discounts for dining and merchandise. You'll be saving a boat load of money by being with her during the vacation - probably in the thousands.
Anyway have fun! Ill check back to see if you have any more questions.