For years I had been searching for my Carrolls in Cork. Besides the names for three definite brothers, their father's name and two possible first names for their mother, I wasn't working with much. I finally found an 1865 marriage intention here in Boston in which Daniel Carroll listed Rosley as his mother's maiden name. I searched Griffiths Valuation and that name is very uncommon and appears only in one small section of Cork. The Church records for that area are only available at the NPL in Dublin. I had the chance to spend a few days in Dublin and with the little time I had I could only go through just a few rolls of film. I found several Rosley marriages and births in that area of Cork, but no marriage of Ann or Catherine Rosley to Daniel Carroll or any children born to them. The area of Cork is is Lettergorman, Kildee and Kippagh. There are no Rosley in any other area of Cork. There was a Thomas Rosley in Griffith in the townland of Kippagh. Since the brothers were born 1830-1840s, I'm guessing Ann Rosley was born 1810+-?????
Because passage to Canada was cheaper, I wouldn't be surprised if Thomas went first to NS/NB/PEI before he came to New England. My Carroll brothers came to Boston in the 1850s but I can't find them altogether on one ship's manifest. If they travelled separately, there would be no way to tell when they arrived or on what ship because the names are so common. If they came through Canada, there won't be a list--either upon their arrival in Canada or when they came to the US through Canada.
I wish I had more. Please keep me updated on your findings.