If you want to replace the old values in the synchronization parameters with new values, clear the previous synchronization parameter values before retrieving data from an MBO during a synchronization session.
CustomerSynchronizationParameters sp = Customer.getSynchronizationParameters();
sp.delete();
sp = Customer.getSynchronizationParameters();//Must re-get synchronization parameter instance.
sp.setCityname("New City");
sp.save();
SUP101DB.synchronize();