Hello! You should be able to move the armies outside of the AI's territory, you just need to make sure you set their movement path to go outside their territory! It's a bit odd to explain, so I've put a screenshot together for you! I hope it helps. :)

Yep that works. The outpost wasn't part of the city right before the battle and was getting ransacked by the army on top of the outpost. The fact that a battle suddenly allows the city to absorb this outpost is what i was trying to report as an issue. Is that expected behavior if you have a battle on a non attached territory that the ransacking stops and they immediately get to attach the territory?