Hi Shane,
I'll try to answer a few more questions.
James McD, with wife Margaret, Michael McD and Maria McD all start to appear in Bilston records from the early 1850s (there may be more and I am sending for marriage certs as and when I can afford it to check fathers' names).
First, our Bridget was born in Bilston in December 1851 and baptised there. I don't yet have a birth cert but there's a letter waiting to be posted to try the one you mentioned.
Neither Bridget nor the Michael in the family of James and Margaret appear in 1861, so I'm guessing may have been left in Mayo with relatives, but there is no birth/baptism for Michael in Bilston and there are census records saying born in Ireland, so I guess at least Margaret went back. Bridget is a bit of a puzzle as all later records suggest she is born about 1854?? but no evidence of more than one in Bilston. There are nine baptisms in Bilston, including twins who did not survive for long.
FCurran belongs to Maria's family and had independently deduced that Michael (senior), James and Maria were related about the same time that I had. However Bridget was born first and James and Margaret were far too young to be the parents of his Maria. We are in touch regularly, including today!
There is another set of McDonough (and variants) families in Bilston in the 1850s, whose parents were John and Bridget (and were also in Bilston) - they are also linked to family names Comer and their Bridget married first a Coyne and then an O'Neil). there are more or who may belong to either that family or ours, or yet another family not yet known.
I have lots of info from the catholic church in Bilston and a number of registration certificates already.