The Igi gives
Thomas quilliam & C Clucas m. Braddan 30 OCT 1810
There are no Margaret Quilliam's with father Thomas I can find -
there is under Thomas + Cath Clucas
John Marown 19 JUN 1814
Thomas David Marown 28 JUL 1816
Eliza Marown 07 JAN 1821

As many manx families considered Elizabeth and Eliza to be different names it is possible there was an Elizabeth as well as an Eliza
The gap between children could indicate missing entries
Are the other children in your manifest

What was the date of emigration ? - most Manx emigration was post 1826 and then generally came from the North of the Island rather than the south

however they do not seem to be in 1841 census