>That's a good point support moves can be used aggressively so: yes? You can also support move their units but only into territories they already control. At least, that's the ruling that would make sense to me.
Just to specifically complicate this, how would that impact the following situation?
I am at war with Player 2 and Player 3, who are allied with each other.
Player 3 is bouncing themselves in a Player 2 centre, to stop my nearby unit taking possession of it.
Given general positions, it benefits me for Player 2 to have a disband, even if Player 3 gets a build, so I support one of their bouncing units in.
As another hypothetical -
I am at war with both Player 2 and Player 3, who are at war with each other.
Player 2 has a centre they will likely lose to Player 3. I have a unit there, but not enough to be able to force my own possession. Due to other considerations (I am actively attacking Player 2 in other locations) I have no interest in attempting to establish a ceasefire with Player 2. However, I consider it actively in my interests to support Player 2's unit holding position as it will deny Player 3 gaining possession of the centre.Can I support hold my enemy?
Personally, I'd say "when at war there are no limits to your interactions with a party" rather than trying to limit "when at war you can only have hostile interactions with a party" would be a much easier way to go about things.