I have the church entry for Margaret's marriage to Arthur and on this she is described as Margaret Conway- alias McCullough and her father is named as Patrick McCullough. However, on the marriage cert obtained from the General Records Office, her father is named as James Conway.
In the 1871 census in Wallsend, Margaret is with James and Margaret Conway (Arthur Campbell is also a boarder in the house) she is named as daughter but from the ages, James is too young to be her father anyway.
I assume therefore, with all the evidence, that Margaret was daughter of Patrick McCullough but was brought up by James Conway and her mother Margaret. I have births of two of James and Margaret's other children who were born in Scotland - Scottish entries ask for place and year of marriage and parents - the parents are given as James Conway and Margaret McCullock and the marriage took place in 1857 in Co Tyrone, Ireland.
So it would seem that Margaret was married to Patrick McCullough and after his death she married James Conway then came to England via Scotland.
I dont have a maiden name for Margaret Conway, however the name Haughey does appear a lot amongst godparents and marriage witnesses, there were also two boarders named Haughey staying with James and Margaret Conway in 1871 which makes me think perhaps she was Margaret Haughey - however I do not have concrete evidence of this.
children of Margaret and Arthur Campbell