I did some searching and didn't find where this had been previously requested, so apologies for making a new post if this is already out there.
 

We would LOVE it if the forms included in completed instances could somehow be set to static, so future changes to these forms don't affect those submitted in the past.
 

Some use cases:

* We had a recent request to remove two table rows from our time sheet form. We have learned from experience that this requires us to publish a new version of the form, because making this change to the live form also removes the rows from old submissions, resulting in submitted values appearing in incorrect rows on instances completed long ago.

* Because we needed to publish a new version of the form, we wanted to set the starting form on the old process to a message directing users to the new form, but because this also changes previous submissions, users will only see this message when trying to pull up the form under "Completed Tasks."
 

When an instance is completed, the forms submitted as part of that instance should be set in stone, and not affected by future changes.