For achieving this
"allowed for flights of up to four aircraft and also allowed the user to insert coordinates into the flight plan so that the AI would follow a specific path."you can't go with AI flight plans. Only via .xml files this is possible because they define all these necessary parameters.
Such .xml files are created either by CCP or FSX/P3D Mission/Scenario system (also can be done via FSCAI scripted assingments).
You can certainly have AI formations taking off and Landing at an airport. That's for certain. They just don't start from parking spots
but from the runway and end (accumulate) at the runway.
With CCP you can certainly have a sort of campaign with many AIs taking off from airports at different times, following their Flights
Wpts to their "targets"-goals and return for landing at the airports.
Such a sample campaign (one day - Normandy 1944 campaign) with CCP directed AI traffic, you may watch here :
www.youtube.com/watch?v=nond9O_1FNYAt 05:35 and 12:53 you can see CCP controlled allied & axis AIs taking off from the airports for their "missions".The only real PROBLEM is that as soon as FSCAI takes control of the AIs (either to engage ground or air targets), the CCP flight Wpts are
cancelled permanently. This is also the case with any other method (Flight plans, Mission or even assignments), resulting that the AIs
after running out of ammo or destroy their targets can't resume back to their assigned route (by any method) and RTB. They just
fooling around or head back to a previous last Wpt and keep going straight.