Just found your post on Ancestry, I am a descendant of Michael C. Mulvehill
We think but cannot prove that your Peter was Michael C's cousin. Peter Ryan was Michael C's son and my gggrandfather.
Unfortunately I disagree with the name of his wife it was Egan not Higgins. I have volumes of Catholic vital records for Cambria county and vicinity the actual record everyone sites reads that both that Peter and his wife were from Huntington County. Your and possibly our Peter never lived in Huntingdon county. He resided in Indiana county until he was fairly old then moved to Wilmore. His wife was an Egan. I am supported elsewhere in the catholic birth records as Egan's appear as godparents of some of his children. Additionally in Indiana county where the majority of the Mulvehill's initially lived there is a St patrick(s) with plenty of Mulvehill and Egan graves. I think they were either married there or possibly in Ireland. Unfortunately Indiana county is not covered in the books I have. Some of the children were christened in Loretto but only out of convenience and not necessarily physically there as priests back then were itinerant.
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