Trying to find Grandfather's family

My grandfather was Bernard Mooney who first appeared on 1891 Scottish census, together with his mother, Bessie Mooney (she was born Bridget McLean), his sister Elizabeth and brother Charles. Their ages then were given as 68,28,25 and 24 and all born in Ireland.

My father always believed that his Dad came from Antrim, but on the d1911 census in Scotland he said he came from Derry.

I have not been able to find a Bernard Mooney (1863-1866) with father Michael Mooney and mother Bridget McLean anywhere. The closest I have come is The closest I can come to is a Bernard born 1854 to \michael Mooney and Bridget Mooney in Moneydig.  I have been to the church in Kilrea and spoen to Father Calgan and the records certainly show that birth, but it weould appeasr that since many of the births had the mother listed with her married name the possibility exists that the maiden name of the mother was not listed bak then.

I went to the old cemetary there and found grave 7b that had a stone erected by thew McKiernan family and I am surmising that if this is my family, then possibly my grandfather had a female relative Susan Mooney who married into the McKiernan family.

I cannot find my great grandmothers family either. She was Bridget MxcLean born around 1823 and her parents were Henry McLean and Bridget Kerry.

I use irishroots, scotlandspeople, & familysearch plus have a family tree on Ancestry but cannot progress further than what I have stated above. I would be grateful if there was anyone out there who could maybe help.  In return if there is any research that I could help people with I would be happy to do so.

Many thanks

Maureen (nee Mooney)