We have a reservation on March 16th and will be celebrating 3 birthdays that night. Do they have cupcakes with candles, or something we can celebrate with?

1900 Park Fare,

Yes they will do cupcakes with candles for you for a birthday celebration.

Just let your sever know when you arrive, they will certainly put on a show and give you some kind of goodie

This is common in all the Disney campus dining spots ( the fast casuals are not set up for it, but) tell your guest services folks at the hotel and they will book it.. too

Best to check directly

Yes but I would call the restaurant prior to your reservation to confirm.