Hi Andy, 
I was a little surprised to find two relations at the time. I found that Sustrans don't indicate that the route will even get as far west as Porthcawl, and that "at the moment, only short sections of the route are open" https://www.sustrans.org.uk/find-a-route-on-the-national-cycle-network/route-88/
I thought I'd wait until more of the route was surveyed by mappers before deciding how / if to merge the two relations.
Kristian