Hi
That's an interesting theory. Below is information I obtained from the Manx.Museum which I think proves that Mary Ann had a brother John James [or Thomas] and her mother was Elizabeth Kneen. She also had a sister Elizabeth Jane who died aged 13.
Some of the Hannay children are buried with their grandparents and great grandmother. Also I realise bapt date can be much later than birth but if MAry Ann was born [and baptised] in 1852 she would have been only 15 when married. Would love you to have the answer and I know it is in there somewhere - but I am stumped at the mo.
Braddan Church
Grave No
3451 Sacred to the memory of Elizabeth Kneen
who died the 13th February 1853 aged 84 years also of John Jas Bridson who died 24th November 1854 aged 3 years also of Elizabeth jane who died 7th April 1855 aged 13 yrs.
Through Burial book for Braddan at Manx Museum which showed who was buried in the grave.
Elizabeth Kneen Feb 15 1853
John Thos Bridson interred Nov 26/54
Elizabeth Bridson Apr 9 1855
James Bridson Nov 14/75
Elizabeth Bridson Sept 3/76
Eleanor Hannay October 14 1884
Bertha Hannay October 10th 1888