As much as I currently know is posted already but I have an uncle (GW's youngest son) who is still alive who I can refer to and maybe obtain more info.
A little is known about the Welch family also plus maybe various branches of both families.
A number of photographs of both exist.
I suggest you get back to me and tell me if you are related and if so how. Also it would be good if you can post any information you have then I can perhaps be more helpful if I can see how you might fit into the picture.