Special cargo missions impossible?

[Q]

Suicide Junkie said:
What about a combat?

Have two fleets of equal strength, and make the player decide which one to help, thus tipping the balance, and diverting the storyline to make the player allied with one of the two powers.

That is the situation where a "choice trigger" would be needed.
Now the only option as Phoenix-D pointed out would be:
"Fly to planet A if you would help race A or fly to planet B if you want to help race B" and then change the allies list accordingly. But the player could still do nothing, wait and see who wins!