Shellyesq, this is really brilliant. Can't thank you enough. I haven't followed through all the links you provided but I've been working on Catherine/Kate from the Welsh end just to establish the link to my Roberts family. I've found her and everything fits beautifully. Her father was Humphrey and her grandfather on her mother's side was Moses Richards - which accounts for her brother's name. She had been orphaned quite young and had lived with an unmarried uncle, a retired grocer and baker. She has disappeared from the UK 1911 census - explained by the fact that she had emigrated by then. So I can now fit her and husband and son into my tree with confidence.
Only one thing is odd - I was told by a relative who gave me the info about her that she had a brother called Humphrey. I found what I think is the tree you mentioned - was it on Ancestry - a 'oneworld tree'. Looking at this tree Kate's only sibling was a brother Moses (this ties in with the Wales censuses). But on the oneworld tree, Moses has a SON called Humphrey born 1901. I wonder if my relative might have got it wrong and Humphrey was Kate's nephew? She seemed very certain and had met Humphrey and his last wife Ella Mae Forman and has a picture of him with Kate and John Lloyd Jones. On the photo Humphrey looks possibly younger than Kate, so possibly she has got it wrong. I will have to get back to her on that one, which will take a while as she is in Australia and we communicate by snail mail. It's a great pity there aren't any sources for the oneworld tree - but someone somewhere must have been tracking Kate and John Lloyd. Seems likely it is one of Moses' children.
I know Kate moved to Marcus Hook shortly after her husband died, so she could be near relatives - possibly her brother's children, so the dates on the obituary tie in very nicely with that. Is the obituary you found on-line? I'd love to see it and was wondering if anyone called Humphrey was mentioned. Apparently Kate didn't like Marcus Hook very much - much more industrial that where she had lived in West Orange. Rosedale Cemetery was where her husband was buried, so the obituary info ties in nicely.
You provided info from the US censuses up to 1940. Does this meant that the USA censuses up to 1940 are available - are they on Ancestry.com? I have Ancestry.co.uk but I think our library has the .com version, so if I know they are available I could go and have a look at them myself. They might give some leads about when and where Kate and John married and, more importantly, who Humphrey really was. If I could establish that it was Humphrey, the son of Moses Richard Roberts, who married Ella Mae Forman I'd know for certain.
I know I would never have found any of this info at all without your help. I'm very grateful. I shall be very busy now following all the leads.