I think the proof can be found in the 1880 census of Waseca Co., Town of Byron; Jerry Maroney, as he was known in public, married to Johanna, with the children at the time, James, b.1868; Sarah G., born 1874; Margaret, born 1875; Katie, born 1878; and Mary, born 1870...I think that this Mary, 1870 is your great grandmother. I also have newspaper outtakes that mention one ofThomas Maroney's daughters taking a three month extended visit to her relatives and friends in MN and other refrences from the paper to the effect that Jeremiah and Thomas are brothers. Jeremiah came to America in 1854, six years after his brother Thomas, born 1827. Jerry lived first in Maryland, then met up with his brother in Beaver Dam, Wi.. He Enlisted in the Civil War and served in Company A, 17th Infantry of Wisconsin. He married Johanna Murphy at Winona, MN on 2 Oct 1866 (she was sixteen!), They lived in St. Mary's township and had nine children, five of which survive or are alive at the 1880 census. All of his children and his wife were alive at the time of his death. He died at Byron, then Waseca County. Now Byron is in Olmstead county. I think we have a soild case for relation between Jerimiah and Thomas.
ps My note to you on Thomas and family is a response to another post you wrote on the Maroney post below this one.