We are experimenting with a permission setup that is intended to block this at the user level. That is, you know which company a user should be able to do transactions and which they should not. It uses a custom event to check whether that user is allowed to do certain transactions in that site based on a particular permission granted to that user. We’ve only done customer order creation, purchase order creation, and inventory moves. We don’t have it deployed to PROD yet though. We did have to create a separate event for each site and each transaction we wanted to trap, so it does have the potential become very hard to manage.
Nothing out of the box to do what you are wanting to do though….
Thanks for replying @ShawnBerk - I was hoping there was something out of the box I’d forgotten about, but seems not! I’ll have a look at an event and see if I can make anything work.