Hi Heather

I can't see an 1848 baptism in the IOM for an Isabella Costain in the IGI --- the nearest is 1853. But there's an 1847 baptism in Liverpool to a Thomas Costain and Mary.

Brian Lawson's 1851 census index doesn't have an Isabella Costain below the age of 20. Can you give some more information eg how has her name and birth year cropped up in your research ? Tell us as much as you know about her already.

Jean C