DOB for the Richard Galbraith who was father of Thomas Seymour Galbraith

Question

On 25 Apr 2020 Philip (Mills) Broughton-Mills wrote on Galbraith-934:

His mother, Rose Trench, was born 1746. The source you're quoting 1759 from is a 1968 article "The Galbraiths of Cappard" by Sir Henry Blackall and also quotes his parents' marriage date of 1770. Based on every other record (plus common sense), either Blackall made a mistake or the Irish Genealogist journal made a mistranscription.

Answer 1

Sometime between his parents' marriage in 1770 and father's death in 1793, matching the 178X birth dates of his siblings.

Comments

It doesn't answer the question as to whom is Thomas' father.  The fact that there was a Richard Galbraith, son of a Rose Trench, does not prove that her son was the father of Thomas or the husband of Livinia Seymour.  Can anyone find proof that Rose Trench is the grandmother of Thomas Seymour Galbraith?

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True. Thomas's father is ascertained by three other sources: Thomas's gravestone, which says he was of Cappard. Thomas's marriage certificate which says he was the son of Richard Galbraith. Thomas's middle name, Seymour, which was the name of Lavinia Seymour, Richard Galbraith's wife. Plus, no records to the contrary.