Harrison ancestors in Banogues

I'm looking for help on learning more about my Harrison ancestors in and around Banoges townland in Galway near Castleblakeney. Questions I'm trying to answer are:

• Great-grandparents Thomas Harrison (abt. 1839 - 1911) & Mary Brown (abt. 1861 - ?)
  • Do their marriage records exist (ca. 1884 - 1887)?
  • Do their birth records exist?
  • When did Mary pass?
  • What other records exist for Mary? Who was her family?
• 2nd Great-grandparents William Harrison (abt. 1809 - 1879) & Unknown
  • Is he the same person as this Griffiths Land Valuation record of William Harrisson in Ballymacward leasing Baunoges lots 4A & B from John H Blakeney?
  • What civil, parish, vital, or other records exist?
  • Who was his wife?
  • Did he have other children?
• Who was Michael Harrison (b. abt. 1850)?
  • Thomas (1839) registered 2 civil deaths on 17 Nov 1879: his father William aged 70, and a Michael Harrison aged 29. They have different causes of death. Perhaps he was a brother or cousin.
• Anything else there is to know about Harrisons in Galway!

Here's what I do know:

My grandfather Thomas Harrison (b. 1902 civil record) was from Banoges, Castleblakeney. I know this from his correspondence with my grandmother Kate Hansbury (b. 1908) who was from nearby Ballagh. However he died young and we never learned much about him or his family.

Through my research I found that he emigrated to New York City, arriving 5 Dec 1927 on the S.S. Baltic, and they married in NYC in 1937. He was born to Thomas Harrison & Mary Brown in Galway according to his U.S. marriage, and naturalization, and death certificates.

• Mountbellew civil birth registration: Thomas Harrison born in Banogues on 28 Feb 1902 to a farmer Thomas Harrison and Mary Brown.
• 1901 Census: Thomas' parents & siblings living in house 3 in Baunoges the year before he was born.
• 1911 Census: Thomas living with his family in Baunoges house 7.
• 1911 Civil death record of his father (my g.g.) Thomas Harrison (1839)

My great-grandfather Thomas (b. abt. 1839) was 63 when my grandfather when born, 13 years older than his wife Mary (b. abt. 1861), and had at least 3 children with his first wife Bridget Murphy (b. abt. 1847, d. 1884):

• John (1880 civil record & parish record) who I think matches the John at home inthe 1901 & 1911 Census (with misreported census ages)
• At least two others older than John, who don't appear in censuses: Catherine (?), William (1874)
  • Possible 1870 civil birth for Catherine, I'm not sure 100% sure of it
  • This may be William's 1874 Civil Birth record, but the database entry is linked to the incorrect image. The same DB record appears in RootsIreland.ie and names Thomas & Bridget as his parents.

Other documentation:

• 1869 Civil Marriage record for Thomas Harrison & Bridget Murphy
• 1884 Civil Death record for Bridget Murphy
• Not found yet: 1884-1887 marriage records not yet found for Thomas (1839) & Mary Brown (1861).
  • It would have taken place between the death of Bridget Murphy in 1884 and the birth of Mary Brown's son Patrick (abt. 1887 according to the 1901 census).

The first marriage to Bridget was a surprise that I was clued to by a random email from a music historian who was researching my grandfather's accordion-playing career. I confirmed the connection between the senior Thomas' families by tracing the immigrations of my grand uncles & aunt. They supported each others' journeys, named each other on Ellis Island ship manifests, and lived together in America. The connections between the half-siblings and their parents Thomas, Bridget, and Mary emerge in their U.S. naturalization, marriage & death certificates.

Additionally, a place named "Glentane" is reported as home by some Harrison siblings in a few U.S. documents. I think this matches Baunoges because Google Maps shows it located at 53° 25′ 8″ N, 8° 30′ 43″ W which is just a few meters south of Baunoges on the Griffiths Land Valuation map.

I would love to find out more about my grandfather's family and ancestors in Galway. Any help and advice would be greatly appreciated!

Thank you,

Tom Harrison from New York