Sorry to add confusion to an already confused picture.

Whilst there is a marriage of Thomas Collister & Isabella Cowin this does not appear to link to the Isabella Collister who dies in 1845.

The 1841 census has
1841 census
Road above Amegary
Thomas Collister 70 ag lab IOM
Isabella 75 "
\\
same place
James Callister 40 ag lab IOM
Margaret 35 "
Catherine 11 "
Ann 9 "
James 7 "
William 5 "
Philip 4 "
Joseph 3 "

and then in 1851
1851 census
Chlyclogh Lonan
James Colister head m 50 holding a small croft Lonan
Jane wife m 23 Maughold
James son s 15 farm lab Lonan
Phillip son 12 "
Elizabeth dau 10 "
\\
Chlyclogh
Thomas Colister head wid 83 Lonan
Ann dau s 42 "

Thomas dies in 1854

Lonan
Thomas Collister Cleiy-Clagh 21/11/1854 87 yrs

If you go back to the daughter Ann and the James next door (who is a son of Thomas & Isabella) you find the baptisms with parents Thomas Collister and Isabella COTTIER

However I can find no Thomas Callister to Isabella Cottier marriage.

As I said all very confusing