New Snelling book includes Tandys
At least two descendants of Roger Tandy and Sarah Quarles married Snellings, and they are included in the Snelling book.
I have a new edition of _The Family of William Snelling and Sarah Scott_ in .pdf format. It includes Vincent Snelling's wife, Adelia Tandy--they were in Oregon in 1844--and Jackson Tandy's wife, Sarah Scott Snelling, who went to Oregon in 1850-51. Most of their descendant families are included in the book. If you are a descendant of Adelia Tandy Snelling or Jackson and Sarah Scott Tandy and want a copy, email me at jimmcmillen/earthlink.net (replace the /). The file is free to Snelling descendants.