Looking for family of Michael Cornelius Wrinn, possible sibling Catherine

Our great grandfather was Michael Cornelius Wrinn.  He was born in County Kerry approximately 1834.  We don't know when he moved to the U.S. but by 1862 he was in the U.S. Army Infantry.  He married Nancy Jenkins (born in the U.S.) in 1875 in East Tennessee.  The marriage produced the following children (listed in birth order) Catherine, Mary Louise, Michael, Julia, Douglas, Jerry, Laura, and Margaret. We have no proof of his siblings names, but found a U.S. newspaper advertisement listing a Catherine Wrinn (sister) looking for a Michael and a Cornelius or a Michael Cornelius.  This appeared to be a common practice in the U.S during this time for lost family members. She advertised his last known location in a small riverport town in East Tennessee.  East Tennessee is where Michael Cornelius Wrinn settled and lived the remainder of his life a couple of counties from the port town Catherine listed. There is a possiblity of another sibling -  John Thomas Wrinn of Vinton, Canada, DOB July 7, 1853 and DOD 1953.  His decendents are sure of the relationship but have no documentation.  A generation preceding mine of both families have met and were amazed at the families' physical likeness.  They have John Thomas Wrinn parents listed as Edward Wrinn and Ellen Griffin. Other family members have a sample of ggfather's writing.  From his penmanship and composition we believe he was formally educated above the average level for the era. Other than a possible family from the Firies Catholic Parish Records which does not list my ggfather in the list of siblings, but has a five year space in the birth list of children, this is the information that I have to lead me to his origns in Ireland.