Hi Marcia,

MaryM has very kindly looked up the Braddan marriage for you (see "Lookup please" above).
She wrote:
Kirk Braddan marriage---no.122 / 11 April 1850
William Kelly/ full age / Bachelor/ Labr./ Ballamenagh / father William Kelly /Farmer
Mary-Ann Wilson/ full age/ Spinster/ Mt. Rule/
father Thomas Wilson Labr. Both signed with their
mark X in presence of John Kelly/ George Clark/
James Corran [apparently parish clerk ---MM]
Vicar Drury.

So forget Isaac Wilson and the Kissacks! The other bapt I suggested now looks more likely, even though she was Mary Ann at her marriage.
The IGI has this extracted record for Mary Wilson with father Thomas:
MARY WILSON Christening: 26 JUN 1825 Kirk German Father: THOMAS WILSON, Mother: ANN SKILLICORN.

If you look at the IGI you will see a number of William Kellys, son of William K., bapt around 1822. Any luck finding more details on other US censuses? Or exact birthdates on their MIs?

Sue