You can achieve this requirement by the below steps:
1- Assuming you already have dialog task for getting the address.
2- Create another dialog task for example “getPincode” with “sub-intent only” option enabled).
The sub-intent dialog can act as a sub-task for a parent dialog task. It will not be listed as the bot task when user requests for “help” in the chat window.
3- In the parentTask say getAddress, after displaying the address in a message node, make a new connection to the “Dialog Task”, select “getPincode”.
As you can observe in the screenshot, after displaying the address, the getPincode subintent is connected. In the chat window, the question about Pincode is answered.
In order to invoke the sub-intent, please set the Hold and resume options from “Manage Interruptions” at the bot level/Dialog level.
Though these steps help you in achieving the requirement, as per your last point in the query, the getPincode dialog task will not be invoked directly by the utterance “what is the Pincode”.
It will be invoked only from the getAddress task.
If you need it to be invoked individually also, then you will need to create a new normal Dialog task for pincode.
Let us know if you have any further clarifications on the above.