Donalyn, The Snellings you mention who came to Oregon from Missouri (Daniel and Vincent Snelling and Sarah Snelling Tandy) are siblings, and they are part of my family. Another sister, Theodotia Snelling Hutchinson (Mrs John), and a niece, Cynthia Snelling Combs (Mrs Richard C), also came, all by 1851. A brother, Benjamin Snelling, and two sisters, Margaret Snelling Ricketts and Jemima Snelling Lightner, were '49ers to California.
I've done the genealogy on all of these people (and some siblings who stayed back east) and have published a book about them--THE FAMILY OF WILLIAM SNELLING AND SARAH SCOTT, 2nd Edition dated Jan 2001, privately published.
I have a copy of Sarah Snelling Tandy's will, but I don't have letters or similar material. Have you run across anything like that at the Historical Society or elsewhere while checking on George Snelling? He is, so far as I can determine, no kin.
Thanks, Jim <JimMcMillen@earthlink.net