Child, #173, considered the ballad related to the story of Mary Hamilton executed in Russia on Mar. 14, 1719. No other Mary's in this story. A Mary Beaton and Mary Seaton acompanied Mary Queen of Scots to France when she was a Child, but no Mary Carmichael. The Russian story, retold in English by Child, doesn't have her pregnant by a Stuart, and the action is all in Russia, not Scotland. I't really difficult to see what more than the execution of a Mary Hamilton for infanticide is common to the story and the ballad.