I am trying to create a mod that adds CS to mercenary armies at certain points throughout the tech tree to make them a more relevant part of the game and help them keep up with advanced units.  The problem is I can't identify a path to add this effect.  I was hoping there would be a validation of "rented army" or something like that for army, but that doesn't exist.  Has anyone successfully done something like this or have any ideas?  Thanks.