Hi Chaitali!
I will recommend you to use call microflow activity inside the nanoflow for committing the RequestRegistration object.
When a nanoflow steps through its actions, client actions are directly executed. For example, an open page action immediately opens a page instead of at the end of the nanoflow. This is different from client actions in a microflow, which only run when the client receives the result from the microflow.
Hope this helps!