Are you fine with other people feeding your child?

Baby is 1 now, and has been slow to eating & his uncle is constantly trying to feed him and I don’t feel comfortable with it, he doesn’t really know what all baby can handle, and not only that, but he feeds him from his same cup or spoon that he’s been eating off already. I don’t know how to tell him not to feed baby. He is not one for subtle polite hints either. What should I do?