I didn’t fully comprehend (or read your page!) but I see you made the crack wider. You can fill that with a piece of ash ripped on your bandsaw, then glue & clamp. While it’s clamped drill holes for dowels all the way through the leg (B). Then put yellow glue in the dowel holes and send them in so they’re sticking out on both ends, you’ll cut them off later. I would guess that anywhere from 4-6, 3/8″ Diameter dowels about 6″ long staggered down the leg (and not too close to the edge). Drilling for larger diameter might take away too much meat from the leg.You would know the size dowels that would work best, better than me. Once it’s dry you can plane the edge of the leg as you see fit as the repair will be permanent and strong, if not stronger than before. If you’re concerned about the other legs splitting as time goes on due to stress you can use this same treatment without a problem right away while you have all the tools in place and the wood’s easy to work on. You can put some dowels from back to front as well, all the way through the back piece and half way through the front. Ash has a tendency to split along the grain, much easier than most other hardwoods. It’s a nice choice for the bench, plenty of weight
