William Sutherland - Did William "the Scot" Sutherland have a wife before Margaret Tosheoch?

I am supposed to be a descendant of Alexander Sutherland, son of David Sutherland (son of William "the Scot" Sutherland) and his wife Mary (daughter of Patrick MacGregorie, the son of Col. Patrick MacGregorie). However according to Geni.com, Margaret Tosheoch is the mother of both William "the Scot" Sutherland's son David and Col. Patrick MacGregorie's son Patrick. That would make Alexander the half-uncle of Mary. I have also seen birth years given for Alexander that precede when Margaret MacGregorie leaves the tax rolls, presumably upon her second marriage to William "the Scot". While not definitive (Alexander's birth years may be estimates, sometimes uncomfortably close marriages did occur), this evidence does suggest Walter "the Scot" Sutherland had a wife before Margaret who was the mother of one or more of his children, including David. Does anyone have any information either supporting or disproving this hypothesis?