You can already do that, jump into a PMF controlled system, in a disposable ship with an interdictor, interdict and destroy all that factions NPC ships, cause them to lose security status, influence and put the controlling PMF into lockdown. Even better is if the PMF doenst control all the starports, because you will end up 100% hostile with the PMF, you cannot land at their starports to do missions for the other factions, but if they don't control all the starports, you can land at another one and run missions for another faction to boost their influence. So your combat patrols/blockading detracts from the influence of the MF, mission running / trading / exploration data / bounties for any other faction handed in at the non PMF starport has a positive effect on the the non PMF's influence, nudge two of them to meet at a level of influence and boom, you've got a control war.