I do understand a release is needed, thus maybe the second set already copied. While the client may be less than business like, I try not to be, especially when I would rather play in the mud.
In my case, I do not communicate with third parties, but it is because there is no reason to pay a third party for help with my software. Even when I fire someone, I provide information how to get the figures out of the software so they can setup their new software, and even though a refund is given, I allow use of the software for several months for transition. It is a bit boggling how many (most) fired folks ask to come back.
Kind professional acts often deflect action. I have been threatened more than once in 40 years, but so far, never served.