Thankyou everyone for all the replies. Carmel, I dont think he married twice, well not that I know of. Here is a bit more about them
John MANGAN brn abt 1822 County Cavan ( from cenus 1851 onwards in Edinburgh and his death cert in 1855, Edinburgh, Says on death that he had been in area for about 10 years, so assuming that they came over to Scotland just after marriage) On his death it states his parents were James MANGAN and Susan MARKIES ...there is a chance the names may not be correct if person reporting the death was not sure.
Mary GALLIGAN/GALLIGHAN brn abt 1824 County Cavan ( again from census 1851 onwards in Edinburgh and her death in 1872 Edinburgh) Her mother came over with them and lived with them so will put her details below. Her father is down as Thomas GALLIGAN ( he died bef 1851 so not sure if he died in Ireland or Scotland) which I think is correct as this matches with her mothers death cert.
Mary GALLIGAN ms McMANUS ( Mary aboves mother) was brn abt 1793 Ireland ( from census 1851 onwards till her death in 1865 in Edinburgh) Her parents on her death were down as Thomas McMANUS and Ann GREENAN. But again the accuracy of this information will depend on the informant on death knowing.
Mary also had a brother living with her in 1861 and he was James GALLIGAN brn abt 1826 Ireland.
Got Mary and Johns marriage details off one of their childrens births.,In Scotland they put place and year of marriage of parents.
Thanks again everyone for all the info, will follow up all the leads you have posted and no, Les, I am not in contact with Gerry.
Susan