****NOTE****
I HAVE A SUGGESTION AND SOLUTION FOR M&B BANNERLORD CO-OP CAMPAIGN, WILL WORK 100%
Imagine scenario, 2 parties of players on the map, One of you enter a battle and you'd have thought "Oh this guy will fight this battle and I will go on my way to this amazing city" NO! Won't work, BUT! This will.. If player 1 enters a battle, player 2 has to enter the battle with them and they can select any companion or soldier in player 1's party.
I mean, Realistically it could be annoying but M&B is a weird game and everyone really wants CO-OP campaign that will work "Decently", This is probably the only solution that would work decently if I'm going to be honest. Their is no way to make a proper "amazing" co-op campaign for M&B, For example: another idea from someone else. "when someone enters a battle / town / village it usually pauses the map (whole campaign), Well don't, change the scripts and unpause the map so it doesn't pause"
Sure... But that's kind of impossible if I'm going to be honest, even if that could work, Huge problem with that is.. Say if you see an AI in battle and you're watching them from the campaign map overview, You can just watch them fight, fight and FIGHT. Now, However if you're IN a battle, Sometimes battles can take 30 minutes, MAYBE even more. Now, In that time, Say if you attack an AI, Battle looks like it's in your favour but it's going to take quite a while to beat them, An AI can just hop in the battle and kill you, Wow, 30 minutes WASTED!
So my idea is probably a lot better, No idea how taleworld is going to implement that system but it's pretty easy, If Player 1 enters a battle, Player 2 has to join