If you are looking for a guarantee that something will be done for your family member's birthday, then I would suggest arranging something directly through the restaurant like a cake, centerpiece, etc. They have some great choices available under the new promo, then you KNOW something special will be done (and there's no disappointment).
Many of the TS restaurants will do something special, but its hit and miss and considered pixie dust if they do. And it varies from place to place.
All that said, my DS celebrated his 13th birthday at Disney this past January, and he had some great surprises from the dining staff at several restaurants. They were:
Chef Mickeys: birthday cupcake
1900 Park Fare: birthday cupcake and a birthday crown
Crystal Palace: birthday card signed by all the Pooh characters
Sci-Fi: huge sundae "on the house", complete with a birthday candle
Mama Melrose: birthday card signed by every member of the Mama Melrose staff, double dessert on a beautiful platter all done up for his birthday, and a commemorative Walt Disney World certificate
He also got a free basketball throw at Dinoland USA in AK, and the bus driver had the entire bus sing happy birthday to him on the way to the park (AK).
Other places did nothing. But he expected nothing, so there was no disappointment!
