the main thing is i have created in workflow execution step as create_request, but While creating a child request using the execution step in wf, i could see it as only MANUAL process available. but i need this to be an IMMEDIATE transaction.So the user will not be prompted in front end for creating a new child request each time. as we have a deciison step before this executon step with "create child req" action in it. Please advice me on this.
Depending on what release level you are running, you could use the ksc_copy_request special command in an immediate execution workflow step. I think this was introduced in 7.1. It is present in 7.5 and later releases.