I'm not seeing any easy way of doing that without backend changes. Although, in the few packages I have on my local instance, all of the Packages that have that line filled in also have a Parent Request listed in the References section. Depending on how you are creating the packages, that may be an OOTB way of getting that field populated without needing to update the db from the backend.
It's an out of the box execution command. I tried taking a look at the execution step itself, but all I can see is that it has a Execution Type of "Built-In Workflow Event" and the Workflow Event is set to "create_package".
I was unable to find a solution other then updating the database.
We ended up modifying our migration process as a workaround. Now, rather then creating a new package the developers are updating the version numbers of the objects within the package if changes need to be made.