So I followed her MF recipe...now the fondant is so stiff not very pliable...my daughter's B-day is tomorrow and I don't know what to do...some advice please

Try working in some Crisco a bit at a time, or some corn syrup a bit at a time will help with the pliability.

you could also try zapping in the microwave for a few seconds...be careful! You can burn yourself if you are not paying attention. Start with a few seconds only...I usuallly only do smaller batches and then knead together...the addition of corn syrup and/or criso is good also.
Good luck.