His father was also John, born 1796. he married Lucy Maria Vicary and they had five daughters and two sons - Lucy 1819-66, Emily 1822, John William 1823-87, Helen 1926, Theodossa 1829, Frederick 1831-71, Caroline 1836 and Henry 1837. I'm going through all JW's paperwork and it's very muddled, but I'll be able to give you more dates etc once I've done it.
It seems it's quite a grand Welsh lineage, but I think the Saint Robert Ferrar part may have been a family myth as surely all saints are Catholic and he was Lutheran, and as you said, there's nothing online about him being a saint!
I'm not sure how to send you the full family tree and the lives of the people on it once I've put it together as it's huge and way too much to type out here. How do we get each other's email addresses without giving them to the whole world?
Tell your brothers what you are doing is very important and they will be fascinated once you've done all the hard work! All our family think I'm daft too, but I did my family's side and they were all thrilled. I wasn't intending to do my husband's side but found all JW's paperwork and got intrigued. It would all be lost otherwise. In years to come, your great great grand children will be interested to read about you!