Definately book a late afternoon high tea at the Garden View Tea Lounge at she GF. She will LOVE it!
http://www.allearsnet.com/menu/menu_gft.htm
Also, this is not an ADR suggestion, but during out last trip, we were at the America Pavilion listening to the Voices of Liberty singers inside the pavilion and they did a special dedication & sang Happy Birthday to a guest there who was celebrating her 80th birthday. Her family/friends must have set it up beforehand. It was really nice and you could tell this woman felt so special, she was just BEAMING!!
You can speak to many performers throughout WDW and they are very happy to set up a little dedication & sing Happy Birthday to guests. and a 70th birthday is quite a big deal!!
Not sure who to speak to at Epcot to set it up-I would just go to the America pavilion and ask a CM who to speak to.
Don't forget to get a Birthday Pin for her to wear throughout her trip-you can get one at Exposition Hall at MK and/or I think at your resort-?? Can someone confirm this?