no that should be fine. what happened?
my most hated movement bug was moving out a group of stealthy raiders who were observing a seige. they were going to attack an adjacent province, but the sieger moved in a few troops from that province to reinforce the seige... so the game decided to have my stealthy army fight his whole seiging force... It was pretty dumb, and I lost a ton of van thugs
forces that were hidden should be exempt from the "which province do the colliding forces engage in" determination