done some further work on the 'Cross sisters' theory:
On searching for every Catherine and Mary Cross (1680 - 1700) there were only one Catherine and Mary with parents of the same name:
Catherine Cross bap 10-06-1679, St. Martin in the Fields, Westminster, London
parents: William Cross and Catherine.
Mary Cross bap 03-04-1683, St. Martin in the Fields, Westminster, London
parents: William Cross and Catherine.
I am assuming that both girls would not be married before the age of 18, thus:
Catherine married in 1717 was born before 1699
Mary married in 1724 was born before 1706
William Cross and Catherine must have married outside London as there are no immediate candidates.
This also kinda disproves my previous post:
'at St Dunston and All Saints, Stepney, London. Burial 30-05-1751,
Mary wife of Joseph, aged 49 (= b c1702)'

Will now search for Marys born 1700-1706 in London
