yes, possible by using the underlying api. But it might cause problems when you screw up your definition/instance
Thanks for your quick response (as expected :) )
Can you please tell me how can I achieve this? Which API I can use for implementing this functionality?
In the sourcecode of jBPM are a lot of testcases where you can see how you can create a processdefinition from java and also how you can manipulate existing ones. There is also a 'command' for updating developed by Bernd Ruckner from Camunda, see also http://www.bpm-guide.de/2008/10/16/jbpm-deployer-for-jbpm-in-enterprise-environments/
If you had a look and have more specific questions, let us know