I Can Thank My Sister.

If I am correct in understanding that Martin and Margaret Carroll's daughter Mary was the wife of Mago William Sheehan, I can thank my sister Gerry.
Martin was born about 1810 in Ireland. In 1881 he died in Iowa.
Mary was born in Ireland about 1813, She died in Missouri in 1889.
Mago William Sheehan was my great grandfather. So, Mary was my paternal great grandmother.

If there are errors in my understanding, please correct me in 'comments' here.
If you care to add related information, please do so in 'comments.'