is there anything else we can try?

Rebe

His ex told my OH that the child was his and put his name on birth certificate (I think) and I think it was his family that had doubts before him and they made him question the paternity. But when she chucked him out, and things went even more downhill and he was more interested in trying to get access than paternity at the time.
I think he stuck his head in the sand slightly, he believes her to be his but I think deep down there is a little doubt, but until she agrees (if she ever does) to let him see the children, it'll just be an ongoing battle.