Random Predefined Objectives Issue - Please Help.

[Aplion]

Hi all,

I'm planning a mission having two linked objectives so please allow me to present it in brief.

The main idea is that after 1st objective completion and (maybe) while one blufor unit (player controlled) will get into a trigger area, the 2nd objective must be appeared randomly in one of three predefined areas.

To be more specific on that, I would like to have populated with enemies (patrols and fixed positions) and also three captured blufor soldiers (hostages), three different areas (farms) and after, as I said above, 1st objective completion only one of these predifined areas will be populated (randomly every time) showing that (position) with a marker on the map.
Mission failure occurs in two cases:
1st case, if our units will be detected by the enemy before even one of blufor units will be present into the trigger area mentioned (1st objective).
2nd case, if all three captured soldiers will be dead (in case our team have been detected before freeing the captured soldiers then some opfor units will execute the hostages) - (2nd objective).

After completion of both two objectives, the mission will be completed, or even better, a small reinforcement enemy group will attack our position during at same time a heli will land nearby our position for team extraction (under heavy fire).
So if our team, with even just one hostage with them, will be extracted ... the mission will be successful.

Note that when one player unit will be near the captured soldiers (in a trigger area probably) these soldiers must be join our group as AIs, without the ability to carry any weapons (they will just following orders as non playable units).

More or less this is my idea and I would like to ask if anyone can help me with that random objectives issue mentioned above (my main problem).
Unfortunatelly my scripting ability is really poor so any help on that will be much appreciated.

P.S. sorry for my bad English and please feel free to ask for more clarifications if needed.

Aplion