Your never going to get them to cooperate with you, so Instead just go along with them. Then think up some bogus excuse to find out what software is installed, and assume any software you haven't given them is pirated.
Then go to all the affected companies and buy the licences from them. Keep all the licences Locked up at the head office. Just leave the branch offices with the pirated software installed.
That way you have the moral high ground (and probably legal immunity), the companies get their money and the branch office doesn't get angry with you.