This is simply Gilbert Grosvenor, which cannot be combined with Gilbert Hovey Grosvenor OR Gilbert Melville Grosvenor.
Gilbert Hovey Grosvenor (1875-1966) was the first full time editor of National Geographic Magazine. His grandson Gilbert Melville Grosvenor (b. 1931) also edited the magazine. As did his son Melville Bell Grosvenor (1901-1982)