thanks for replies Tara. The person with the family tree on Ancestry is the distant relative who is investigating the Mannion/Mannion route rather than mannion/Mulligan. I had a eureka moment when you mentioned Grandads birth cert as my MiL, who is still alive, has some documents she keeps at our house. I looked today and there it is, the birth cert, showing that grandads mother was indeed Bridget Mannion, formerly Mulligan. So, now I know which name to research, but still dont have any further information. The only clue I have is that on one census Bridgets birth place is listed as Meo, which I presume means Mayo, but Co Mayo is a big place, so not sure where to look.