The only problem is that Captain Samuel Blyth marries Emma Dartnell in India around 1856or 1857. None of his children are named Samuel though, but he, his father, and grandfather all bear that name, so he seems to have broken with the tradition, unless his firstborn son was the Samuel Jr. living in Ireland.
http://www.john-attfield.com/paf_tree/attfield_current/fam747.html^That pedigree has Captain Blyth, his father, Samuel Blyth, but ends there and doesn't have his grandfather but I've seen one source that says his grandfather was the Captain Samuel Blyth of the HMS Boxer who died in 1813 at the age of 29 in the War of 1812.
So it's all kind of confusing, especially with the lack of documents and the people who would probably know more having died too early. I know up until the 1860's, I think, although interfaith marriages were legal they could not be performed by a Catholic priest, so looking to the Catholic church for marriage records of Samuel and Fanny probably wouldn't turn anything up. Is it possibly my Sam Jr. was illegitimate? It doesn't say so on his baptism record, but he has no siblings, so could Fanny McVity have been Captain Blyth's mistress and when she came back to Ireland maybe went to a parish where no one knew her (maybe hence why I can't find other McVitys in Belturbet) and just lied that her husband was out in India? Maybe Sam Sr. sent money for his son to be apprenticed as a shoemaker and to invest in his store? Or maybe Sam Sr. and Fanny were married but Fanny died giving birth (she's supposed to have been sick when she came back from India) and Sam Jr. was raised by Catholic relatives?
For what else it may be worth, there is a McVity family in Belturbet in the 1901 census, but they were Protestants originally born in Fermanagh. Also, Captain Samuel Blyth died in Malta in 1880, so that fits Sam Jr.'s wedding certificate of his father being dead by 1881. My second cousin I met through the internet says that Sam Jr.'s daughter, Mary, went to visit England in the early 1900's, either to Bath or Bristol, she can't remember, and went to a large house looking for relatives of the Blyth's, but a housekeeper told her the family was away in France at the time, and that's the last I've heard of any possible connections.
So if anyone has any possible information the the McVity's of Cavan, specifically Belturbet, or also the Blyths I guess, I would really appreciate it. Also maybe how tense interfaith relations were. I know the Presbyterians were also restricted by the penal laws, so maybe Fanny was from an Ulster-Scot family and when she had a child by a (probably) Anglican, she raised the child Catholic instead. That sounds less likely but I'm just trying to make sense of the situation of all the McVitys seeming to be Protestant and her raising her half-English child Catholic.
Anyway, thanks in advance-
Nick