This is what I meant: the center where the four medallions join creates a different motif. I was just playing around this morning and this is what I came up with.
Don't think I'm completely happy with it yet and it's quite small so I may adjust the proportions, scale it up a bit. I did this very quickly so it's not the best tatting. And of course, I had to put in some Josephine knots, now I know how to do them more easily!