In my case, I want to have a sort of "mercenary" party set up. Where you may recruit a number of different characters, but they are only contracted to fight for you for a certain number of battles. So for example, I could define in the options "When Actor 2 has fought 20 battles, run common event 2", and common event 2 will run the scene where Actor 2 leaves your party after the last battle. I don't think just having parallel processes will work either since it doesn't track actor-specific statistics normally. For example, I think it can tell you "Your party has fought 20 battles" but not "Actor 2 has participated in 20 battles", and that's what I need.
But this kind of script could be used in a more broad way as well. It could also run a common event if you take x number of steps while Actor 2 is in your party (for example, Actor 2 will stop you and ask to take a rest after taking 500 steps in your active party), or if you've gained x amount of Gold with Actor 2 in your active party, he may ask to borrow some.
Is there a script to achieve this? If not, could someone make one?