hopefully you have already got answer to your question from some other source, but here's any way how I update DbAdapter configuration.
I generate deployment plan for DbAdapter in development time by admin console like you have done.
Copy the deployment plan to production environment, then use wlst or weblogic.Deployer to update adapter:
source <domain location>/bin/setDomainEnv.sh
java weblogic.Deployer -adminurl t3://<admin-url>:<admin server port> -user <admin user> -password <password> -update -name DbAdapter -plan <db plan location>/DBPlan.xml
This way I can do my production environment deployment script based, no need to use GUI.
It's also possible to use wlst instead of weblogic.Deployer, but haven't tried that yet.