I've never seen construction like that. Very hard to tell from the pics of the plans but every fuse I've ever built there would be a doubler that goes over that joint shown on the plans. Study the plans carefully before gluing. As far as gluing them together, I would just use thick CA for the time being. After you've got the fuse farther along and you can know what else goes in that area, then put down a 1" or so doubler right over the seam but only after making sure nothing else goes there first. I would just use thick CA for the seam as well.
Carl