When I make the first loop, of a double twist flemish string, I use an alligator clip, or bulldog clip(even a decent sprung peg will work) to secure the join, then just twist the other end, same as the first and it doesn't unravel. Once the string is done, I wax the braided sections then pre stress each end separately to lock in join of the braid. I repeat the pre stressing again as a unit, end to end. You can now string up your bow and not have it try and untwist.