For the record, I changed my Extension of Stay (which originally many years before was a Non-B visa) from employment with a work permit to marriage in late 2021 at CW...Needed an employment termination letter & work permit cancellation document to sort the first part out, then just applied for the marriage extension straight after that before the end of my stay date...From memory the bank funds did have to be in the account for the 2 months prior, which wasn't a problem in my case.