I’m going look at the same thing. 

I found one way to close parent ticket when all child tickets are Closed. It can be done by using the app Parent-Child Synchronization. It will be applicable to all parent ticket types though. If you want only Onboarding bundle ticket to be closed and not others, then it can’t be done.

ya I saw that as well. Didn’t test it. 
We can hope the function to close the main ticket in the onboarding vill implemented.  

I have tested it. Working fine. Any parent ticket gets closed if all child tickets are closed irrespective of the ticket type.

We use this as well, and it works great for Onboarding tickets. It even adds the notes of the child tickets to the parent so the person who is monitoring the overall onboarding process can stay updated without having to navigate to each individual ticket.