Hi Linda. Yes, Enoch Fleece and David McFann were inlaws. Enoch Fleece's sister was Mary Fleece and Mary married David McFann.
Enoch Fleece and his family were in Berkeley County, [W] Virginia prior to their emigration into Ohio in the early 1800s.
I don't know if there would be a familial connection with the Smiths but there is a Smith surname 'match' in the case of Enoch. Enoch Fleece and Mary Fleece McFann's mother was Rebecca Smith prior to marrying Jacob Fleece. Rebecca Smith's father (this would be Enoch's grandfather) was William Smith, Sr. of Berkeley County.
There are a number of land transactions between William Smith and the Fleece family in Berkeley County between 1778 - 1789 . Family relationships extracted from these documents show that William Smith and his wife had the following children: Susannah, William Jr., Solomon, Elizabeth, Mary, Hannah, Rachel, and unnamed who married Michael Gray.
I don't know if this family will align with your own, but it may be worth pursuing a bit further.