I don't know if this will help you, but I too am stuck on learning more about my great Grandfather and family.
John McDannel b.1844 Ireland and brother Lawrence (or Laurence) McDannel b.1846 Ireland. Arrived in 1850 and lived in Ulster Co. NY with Ellen McDannel b. (around 1830). Then moved to McLean County IL in 1865. John married and had children, Lawrence did not.
They went by John and Lawrence McDonald, but we have their naturalization papers that show it was originally McDannel. Also the passenger info on their trip over was with a Edward McDonnel, Ellen McDonnell, James, Michael, John and Lawrence McDonnell.
My grandfathers' written history (John McDonald (McDannel) stated he came over on the ship with his brother Lawrence and no mention of his parents. He stated his family sent them to the US to live with relatives. Therefore we do not believe Ellen or Edward were their parents.
Don't know if this helps you any. If you could shed any light on my situation I would greatly appreciate the insight.