I agree that they may be related, but as far as I know our Henry Agar came to the US during 1848 and settled in Southern Indiana at Evansville. He was married to Eliza Connor in 1851. He was born in County Carlow and she was born in Castle Pollard County. Henry died in 1870 and Eliza died in 1905. Both are buried in Princeton, Indiana. One of their children, John W. Agar (my grand-father) and Mellie Voorhees were married in 1879 in Princeton, Indiana.The other children were Fanny, Charles and Henry .
Amazingly, the story is quite parallel even if the timelines are a bit different. Many thanks for your input and I am happy to communicate further.