This thread has all the necessary ingredients to be a train wreck.
Life is full of disappointment. Hell, I wake up every morning disappointed that I am not rich, thin, good looking. But I get over it and move on with my day.
Disney says you can't go to BBB if you are over a certain age? So, you are disappointed. I get that. Did they also say you could not do ANYTHING together as a mother/daughter combo? IS this SERIOUSLY the ONLY thing your family can do that can make you happy? As people have stated, go to a spa. Go to the high tea. Better yet - take the money you would have used on this excursion and donate to a worthy charity in the area and then spend the time doing each other's nails and hair. You can buy the glitter, colors, etc at home and bring it with you. And the money you donate will pay it forward and bring happiness to someone else.
The important thing is to be together. Not what you are doing - yea, it might have been fun to go to BBB, but you can't, so find something else.
This morning I head a former coworker passed away from brain cancer. Her son is in his early 20s. You think he wouldn't give anything to spend even 5 more minutes with his mom?
Look at the priorities and not sweat the little things. Not trying to disparage, not trying to belittle, just don't get the angst over not being allowed to go to BBB.