I need to share a PDF of some confidential documents of our business that are integral to finalising a deal with a new partner. They need to view these documents before they can sign an agreement

I can ensure that they cannot copy, edit or print the PDF, but I cannot stop them from downloading a copy and storing it locally. Even though this copy would also be uncopyable or unprintable they would be able to share their local copy with other people if they shared their password too.

It would be a good feature to stop a local copy being saved, so in the event we decide not to go ahead with the deal I would still have full control over my confidential documents