John
You should add in the 17thc broadside for No.20. which Child gave in a later vol. Are you working from the Loomis edition or the Dover or an earlier edition? If you're using Dover like me you should check the appendixes as well. It wouldn't take long.

There are lots of late 18thc garland versions of Captain Wedderburn's Courtship, mostly using the title 'Lord Roslin's Daughter' or similar.

I'm also pretty certain there are several printings of Young Beichan from the 18th century in garlands.

Brian,
I have access to a version of GGG but it's on a lengthy disc and may take some finding. I seem to remember there's at least one edition online, Goole Books or Gutenberg or one of the universities. I'll have a look anyway. The one I have access to is more likely to be the earlier edition.