When a player is offered a mission, he is usually presented with a yes or no option.
Is there any way to immediatly offer a second (or third, or fourth) set of yes or no offers upon clicking a choice?

Is it possible to do this in flight?
Is it possible in flight without date posting?

The only way to be offered a mission in flight is to hail or board a Pers, and each pers can be linked to only one mission. So that kind of limits things.

I have also wanted a way to have a series of yes/no questions show up in the bar, but it seems that the player has to take off and land between accepting/refusing them, though I admit my studies were not exhaustive.

Try making them all start out available, and then disable them as neccesary. Note that I have never tested this, and this depends on careful ordering.

Edwards

As far as I can tell, you can only accept one mission at once. This is annoying if you have 2 or 3 invisible missions all set to fire when you land on a planet, but only the first one gets a chance to. It also looks like the choices can only branch until you say yes. Still offers some posibilities, but not all that much...