How to detail with a triangular intersection.

Mason Road joins Halfmoon Carlson Branch 2 (hereafter HC) in a broad triangle. E.g. North bound traffic on Mason can turn left at a fork, then 200 meters later merge onto HC westbound. Or they can turn right at a fork and merge 200 meters later on to HC eastbound

Normally both of the branches would be considered part of Mason Road. You can’t merge at a non-end point. I think I need to add the extra chunk to a ‘way’ including the rest of Mason, but I don’t really understand ways yet and how to add/edit them.