My Thomas was born in 10 Nov 1836 in Leperstown, Waterford, Ireland. He lived in NY near Yonkers for a short time. Not sure how long- he went to London, Ontario, Canada near Ingersoll and Durham to live for a couple of years prior to coming to Davis County, Wisconsin then to Door county Wisconsin.
My Ronans are from Waterford. It was reported that no other family members migrated to the US. Just the uncle and my Thomas. I don't think it is the same Ronan family. The canadian research was mostly done offsite from ancestry, but just using google etc and the libraries etc.. I was able to connect the uncle in canada to the nephew (Thomas) by searching this way. Good luck to you.