If you wind up going to the restaurant to celebrate SIL's birthday, do call ahead and talk about menu options. My SIL has to do this often with her daughter, who has celiac disease. Most restaurants are happy to accommodate her, the point where they'll fry the child's French fries in a pot of fresh oil so there are no issues with cross contamination. Call the restaurant at about 2 p.m., before the rush begins.
I was recently talking to the executive chef of a local seafood restaurant, and I sheepishly admitted I don't like the taste of seafood. He said that just about any seafood entree can be prepared with chicken breast. It's not on the menu, but he takes pride in satisfying every patron, even the picky ones who are dragged to seafood restaurants by relatives and friends. I think he welcomes the challenge.