2 things i wonder if it's possible somehow to do:
- make airplanes go in guard mode over Airfield automatically after ammo being recharged
air forces should be always ready and good players always put them manually on guard to use fast when needed. the problem is - here you used one or two for attack and you again need to back to Airfield, select all planes and put them on guard -over and over again.

- make infantry occupy closest empty vehicles, like transports or killed-driver vehicles.

have anybody ever heard/seen such possibilities?

it might be possible to add a rudimentary AI to some units. I'd suggest looking at other units (especially turrets) for the aircraft guard.
I doubt you could make infantry automatically load into vehicles. Plus if you played as America that would get annoying as you wouldn't collect supplies.

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can you please name some turret i should search in?

yet i was thinking if it's possible to use some module for Airfield, that distubs planes constantly sending them in air, or module for planes to auto lock for guard, so even if it used all ammo and went for recharge it comes back to set place of guard.

You could set the aircraft as slaves.

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