Hello, I probably should have specified:
1. You count the number of VPs each defending player has to determine if the two defenders fight one last round or if they want to agree to a draw in a way. If the players fight, the defender player that wins the final fight, gets the total VP scored by both defenders.
2. The mission was made with a campaign or tournament in mind which is why the defenders may want to share to both progress, or if one has more VP they may want to keep it for themselves and not share.
3. Winner for the last round between defenders is just between the defenders and is decided by how many units can be shaken or routed. I think I had this in mind when I wrote it but never actually wrote it down.
The story behind it was two factions fighting over treasure or technology on a ship, then a much larger force arrives to claim it for themselves. So, the two factions join forces to fight the larger one. Afterwards, they can agree to share the treasure or fight to claim it all for themselves.
Hope that helps clarify somethings.