Thanks Steven for your answer.
Finally, I decided that a new button in the toolbar right beside the "change status" one was sufficent for our needs. It is not perfect but saves a click or two. I asked the stakeholder if it was ok and the answer was yes! User won't search for "Authorize Sites" in the "Select action" menu if he knows where the button is in the toolbar.
Before going in production with the waranty contracts application, we will provide a guide to our users that have permissions to limit any kind of risk.
Once again Steven, thank you!
Danny