Peter Lynch - Looking for Isaac Lynch

Hi, I am looking for Isaac Lynch born in Ireland in 1750, my research has him being Peter Lynch's older brother. He came to America too, but not sure when. He married Anna Blankenship in 1841 around Danville, ILL. They had a son , Francis Marion Lynch in August 1842. Then something happened with Isaac, as research shows that Anna then Married Orlando Lane in 1843. They had 13 children together. I have found these graves, but nothing on Isaac. I did find the marriage records of Francis Marion and wife Martha Cochran, Anna and Isaac were their witnesses. They married in Indiana in 1865. I can't find anything else about him. Francis Marion Lynch is my Great, Great Grandfather. Would appreciate any help. Thank you conniejo357@gmail