Hi Aman,
If you're generating the virtual service from a WSDL, the most common use case is you wouldn't have access to the live system so it wouldn't make sense to have the live invocation step. The thought is if you have access to the live system, the most common approach would be to create the virtual service from recording, which would generate a model with the live invocation step.
That said, you can create a model that does what you want (including extra steps such as live invocation, logging. Pulling external data, etc). Treat this model as a template. When you create a new virtual service from a WSDL, delete the generated model, then copy and paste the template model. Rename the copied template to a desired name. In the renamed model, configure it for the new service image and live service.
Sincerely,
Casey Best
Sr. Principal Consultant
CA Service Virtualization – Application Delivery – CA Technologies Canada