Looking for the parents of Dennis, Martin and Patrick Maloney and their homeland in Ireland

I'm looking for the parents of brothers, Dennis, Martin, and Patrick Maloney (Moloney, Molony, Mullowney) and their homeland in Ireland.  I'm focusing on Tipperary, Clare, and Limerick. Dennis was born in 1818, Martin in 1826, and Patrick, my great-great-grandfather was born about 1836.  I'm sure there were other siblings as no Irish family is likely to have only three sons.  It is recorded on the U.S. census that Patrick immigrated in 1844. I have been unable to prove any immigration dates. Although, it should be noted that my Patrick was not a stickler for exact dates. His age varies sometimes by five years between census. He may have not known his own birthdate. He may have immigrated through Canada, according to the family story.  According to YDNA, our Maloney line appears to be genetically part of the Irish Type III group. 

I have a record of Patrick and Mary Welsh married in 1857 in Xenia, Green, Ohio, but because of the common surnames, I'm not positive they are the same couple. Their first son, Dennis (namesake of his uncle) who was my great grandfather, was born in Lower Canada in 1857/58, the next son Joseph was born near Dubuque, Dubuque, Iowa in 1859/60. By 1860 Patrick and Mary Ellen (Welsh) Maloney had bought a farm and were living near Watertown, Dodge, Wisconsin. The next 7 children, Thomas, Maria (both died in infancy-baptized at St. Bernards in Watertown-the closest Catholic parish at the time), Patrick Jr., Honora, Mary Ellen, Catherine, and John were baptized at St. Josephs of Richwoods. They moved to Ishpeming, Marquette, Michigan in 1874. Their last child, Stephen Christopher, was born there in 1878/79. In Michigan, the family worked in iron ore mining. 

Thank you for any thoughts you may have on my Maloney family.  

Muriel