It's been a few years since you posted this, but I think I have some information for you. My Great-Great-Great Grandparents Christopher & Mary (White) Jewison emigrated from Hull England in 1848 with their oldest children William and Ann. They were in Mapleton WI at the 1860 Census. In Wisconsin they had Henry James, Jane, John, Ellen, and Christopher. They moved to Janesville MN by the 1870 Census. It seems to me that this youngest son Christopher (b. abt 1862), who married a Susie, is Roy's father.
This would make my Great Grandfather Arthur (William's son) and your Great Grandfather Roy first cousins (and we would be fourth cousins).
Let me know if you are still looking for information. My dad's cousin did a lot of research back in the 80's and we have a large book of information. The best of it includes a family tree that traces the Jewison name back to the 16th century in England, a photo copy of Christopher & Mary (White) Jewison's marriage certificate, and a photo copy of a picture that includes my Great Grandpa's cousin Roy...must be your Great Grandpa.
Margaret