Can I decline to lead grace at a family meal while still joining them at the table?

Dad asked me to lead grace next Sunday. I said I'd rather someone else did it. He looked disappointed and said, "It's only a few words. Your grandmother would love to hear you."

My family knows I no longer share their faith. I still visit, sit quietly while they pray and enjoy the meal. I've tried to make clear that I respect a tradition that matters to them. Leading the prayer feels different from being present for it.

Dad thinks I'm turning a simple family gesture into a statement of distance. I think saying words I don't mean would be a different kind of statement. I don't want the meal to become a debate, and I don't want my grandmother told that I refuse because I don't care about her.

How would you make the distinction kindly? I can offer to welcome everyone or thank the people who cooked, but I don't know whether that would feel helpful or like rewriting their tradition.