While creating a PR can we default the requester to blank, so the user will be forced to change it

Summary:

While creating a PR can we make the PR Preparer field defaulted to Null, so the user will be forced to change it upon PR creation.

Content (please ensure you mask any confidential information):

The Business use case we have that the Preparer will not be the same as the requester, and to avoid data entry errors from the preparer to forget to change the Requester, we are looking for a way to force the user to change the requester upon PR creation. The first thing came to my mind is to make the Requester field to be defaulted to null, and since the requester field is required, the system will alert the user to enter the requester. If someone had this case and can help.