https://community.bistudio.com/wiki/allowCrewInImmobile

This is long time resolved.

Where i need to put this lines? I'm not "advanced user", i create simply mission, so this feature should be implemented automaticly.

I suspect your mission is made only in editor view as you said you're not advanced user.

That would mean that you place:

this allowCrewInImmobile true;

Into all vehicle init lines you want to be affected by it. These init lines can be found in the menu when you double click them.

Ofc I haven't used it and only went with this knowledge of it working:
"
Description: If true, units can be in a vehicle with broken tracks/wheels.

Syntax: vehicle allowCrewInImmobile bool

Parameters:
vehicle: Object
bool: Boolean
"

But they will be in vehicle even if hull will be hard damaged right? I just want to make them sit inside vehicle if tracks or engine is damaged, if hull or turret is not operational, they should disembark.

Well as I said I haven't used it myself and the description says:

"If true, units can be in a vehicle with broken tracks/wheels."

So you have to test it yourself.

Tested, working, but how i can do this on campaign missions or single player missions!? This must be reworked. Game is totally unplayable in my opinion. Im getting killed for most stupid reasons - my tank are flying straight under the enemy fire from the cover (PhysX failure from 2 years!!!!), my tank cannot reverse - it starts rotating showing weakest parts of armor to the enemy, or just like 4 minuts ago, my crew disembark under enemy fire from small arms, apc's and tanks just beacuse they have damaged ONE track! How this is possible to create such behavior!

I agree Fighting Power for the disembarkation part. This shouldn't be automatic for your own team and your self. Especially because there is an ejection option in the action menu. So this should be player's responsibility to eject in time!!! maybe in damaged vehicle ejection of the player should initiate the ejection of the AI crew.

But I disagree with the idea of the crew fixing the vehicle from the inside. This is unrealistic as possible.

From the inside? I wasnt writing it..... read it one more time. I was writing to make crew to repear track - for now only enginer can do it.

Ace 3 fixed this for Bohemia - BIS should apply same feature as ACE 3. Mechanic can repair engine, tracks, gun, etc. but no hull or turret. Those parts can be repaired only with enginers. BTW why i cant repair Commander MG (AA)? ANd Ai still are disembarking beaacuse track damage, untill they get "allow crewinimmobile true" script, but on downloaded scenarios its too much work to get implemented.

OK, i found the issue and its easy to fix for Bohemia. WHEN I"M THE COMMANDER, i'm not forced out of tank when track being damaged, BUT WHEN THERE IS AI COMMANDER I"M FORCED OUT OF TANK BEACUSE TRACK DAMAGE (!!) STRAIGHT UNDER ENEMY FIRE (!) EVEN IF TANK IS STILL OPERATABLE AND IN GOOD CONDITION (!!!!!!!!!)