Hi there,
Just wondering where you have found the details for their 1855 marriage... Is it from the birth certs for their children? Do you have the arrival information for either of them to NSW ? Civil registration of marriages commenced in 1856 for NSW, although of course Early Church Records start from 1788 ish....
Some of Wesleyan Archives are located in Sydney, at the former Burnside Homes just off Pennant Hills Road, North Parramatta.... but I am not sure of their current holdings... its several years since I last spent some time trawling through their archives..
Images of the ECR records are on film at the NSW State Library, but that's also located in Sydney and I now reside "up the coast"... It is likely that I will be at the State Library sometime in the next few weeks, but I would need some more clues about the couple so I could figure out which film to trawl through....
Cheers, JM