I just read through the Terms and Conditions on the Disney Visa website. Item #5 states:
"Disney Dream Reward DollarsSM accrued in a Program account, together with any rewards certificate and/or rewards card issued, are not the property of the Cardmember, and cannot be bought, sold, encumbered, transferred or extended in any manner whatsoever (including upon death, as part of a domestic relations matter or otherwise by operation of law). Any Disney Dream Reward DollarsSM accrued and/or in the Program account shall be permanently forfeited upon the Cardmember's death."
Personally I think those terms stink.
Anyway - I have $20 in Reward Dollars. There is no identifying information on the certificate, so I can't see why you couldn't use them. It doesn't say you have to show your Disney Visa when redeeming.
I would go ahead and take them with you - then when you check-in, apply them to your room account. You could buy things in the parks or resort gift shop and charge to your room.
Even though they have a certificate # on them, I can't see how they (Bank One) would track who bought things with them. Especially if you were in a gift shop and bought something and didn't use a credit card for any cost difference. So as far as they would know, your MIL could have used it.
Hope this helps - it was nice of your MIL to give you this gift - have fun with it!
