Thanks Brian - It really does look like the "2 Families" scenario is right.
I had a William Cowell m Jane Cromwell at Braddan 20 Jun 1874 noted from searches today but stupidly forgot to note the source - it has to be IGI, your site, Manx Notebook or ancestry.
Also like you, I cannot locate a Fanny or Frances from the information I can get my hands on. perhaps it was one of those where a middle name was used instead of a first name?
Have you the info for the Tynwald adress in 1901?
thanks for persisting with the search - much appreciated.
regards
John