Clare,
Despite continuing to look for more info on Patrick Gagen, I am at a wall. The only records I have been able to find have been census records (1870 to 1900). I have tried to locate him in an 1860 census without luck. The same with immigration, military, and other records. It is as if he just appeared! I think the spelling of his surname was probably altered, which also presents an issue. Because of these challanges, I have not been able to locate any other family besides his wife and children.
It seems that you may be onto somthing because Gagen/Gegan is not a common name, and it seems like more than coindidence would place two similarly named persons about the same age, in the same area, around the same time. Perhaps if they are related, they immigrated together? If so, this might make an immigration record a lot easier to locate.
I moved away from researching him because I got frustrated, but with your info to consider, I will re examine this branch. If I learn anything new, I will let you know.
Thanks,
Sara