I think that vendors and distributors need to be reasonable here. Many
libraries don't have a good understanding of the concepts of public
performance at all. I should think you would be pleased to have received
a PO requesting the rights the library hopes are available. They'll
never know what happened if you don't tell them.
I suggest that you need to take some time and make a few standard stock
letters for your files. Leave a blank in the line for TITLE etc. and
then when this type request comes in you can indicate
NO PPR for this title;
YES PPR included with this title;
PPR are available at the following cost: $________ . Etc.
Then, as time consuming as it might be, I think you need to respond to
potential purchasers and give them the essentials of what you can sell,
and what it costs.
Just my two cents.
Regards and Happy Holidays
Cuyahoga County Public Library
2111 Snow Road
Parma, OH 44134