Hi Tim

There are many User Submitted Genealogies on the LDS IGI for your Isabella. But you should always be careful with USG's.
They show christening January 1, 1826 in Patrick IOM ( so maybe born Dec 26, 1825) and indicate that parents were Thomas Kelly and Catherine Kirk (Actually Quirk). They give Thomas birth year 1802 and Catherine's 1806, which is very wrong. Also states Isabella died 1879 not 1899. They were born around 1790.
Thomas and Catherine married January 22, 1814 in Patrick. Children I could find:
May 27, 1810 Catherine in Patrick - but could find no death
October 16, 1814 John in Patrick
December 31, 1815 Catherine in Patrick
August 3, 1820 Jonah in Arbory ( Buried Dec 9, 1820)
As Sue pointed out Kelly/Kelley very common on the IOM, as is Isabella, Catherine, John and Thomas.
I cannot find this family on the UK 1841 census on the IOM. Which gives credence to being this family, however could not find them on 1840/1850/1855 US Census reports.
Do any of the US MC's/Dc's/Census etc show what part of the IOM Isabella was born ?
Charles & Isabella m 1854 Kentucky ? Children John 1855, Charles 1857, Antony 1859 etc

Cheers
David Dwyer