I have a marriage cert for Mary Ball, Father John Ball, Dairyman( a minor in 1875 when she married) William Mercer. This is most likely the same Mary Ball you found born 1858 which would make her 17/18 when she married.
James born 1847 is most likely her brother, he married Sarah Mc Donnell in Nov 1875, (have this cert)
John Dingle (9) on the Ball Family 1911 census is a (nephew) of the family, but not sure of who?'James or Sarah?
James and Sarah's son James, is the James Ball and Mary KATE O'Reilly you see in the 1911 census. The Ball family are all direct relatives of my husband. Mary Caroline Ball (known as Caroline) and daughter of James and Sarah,was my husbands grandmother. Love to know more about the Dingle connection.