Sorry not to have responded before but I have been busy on other things. I cannot recall what we have talked about before (I seem to have lost your previous messages and your email address) so I may be repeating myself!
I have records of John and Mary in the 1881 census where they are shown as being in residence at 77 Commercial Road, Bedwellty, Monmouthshire. They have four children but not a James John (who your mention in one of your other postings). Also, this suggests they did not emigrate to America until after 1881.
I have found a Charles born in Frome in 1839. This could be the brother you are looking for. His middle name is Flower and there are a whole series of people in my records with the same middle name who appear in the London area. This Charles could be their ancestor.