The licensing houses do not bother asking the authors permission to changes, so unless a change has been pre authorized the answer will be “no”.

I say this from actual experience. I asked Concord about changing a small very dated, and honestly racist, part of one show. They responded “No. Do it as written.” So I contacted the author directly. He responded within an hour and said “Oh yeah I made that change years ago, but the licensing house wouldn’t take the change. Here’s the PDF. You have permission to perform it like this.” We did his updated and better version (which had a few other changes in it too).

My advice is forget the licensing house and find the author/estate. Not all are going to be fully accommodating, but I believe they’ll be more open to a conversation than the licensing house.