Ally in another war helps nation you are attacking

[Immortal Impi]

I was playing the Emirate of Toledo and invaded the Abbadids(Seville). They were, at the time also embroiled in a war with France, in which one of their allies was the Hammadids. However, I noticed something very strange happening.

Despite the fact that they were not hostile or at war with me, their stack followed the stack of Seville all the way to where I was sieging and fought me with Seville. This despite them clearly not showing up as red when I hovered over the unit spite for Seville. They pretty much followed the Seville army in tandem, fighting me multiple times and even sieging with them.

I am almost certain this is a bug, and hope it gets fixed soon.

( I am playing with Sword Of Islam, no mods).

 

[Sian]

WAD ... if linked together allies in one war is willing to help in another ... it wouldn't make sense if say Norway and Denmark worked together against England while Scotland warred Norway, and met a army consisting of Norweigians and Danes, and the danes said "you know what ... we're not warring Scotland so we just sit here on the sideline watching you get killed, and not be big enough to complete our objective afterwards"

 

[Immortal Impi]

WAD ... if linked together allies in one war is willing to help in another ... it wouldn't make sense if say Norway and Denmark worked together against England while Scotland warred Norway, and met a army consisting of Norweigians and Danes, and the danes said "you know what ... we're not warring Scotland so we just sit here on the sideline watching you get killed, and not be big enough to complete our objective afterwards"

Then the game should somehow represent that instead of confusing us by not showing them as hostile in any way. They moved as though they were one solid unit; enemies, especially Muslim enemies, don't do that. the Hammadids would split off and go home, not march across 5 provinces to fight in a war they're not involved in.

 

[Red-XIII]

WAD ... if linked together allies in one war is willing to help in another ... it wouldn't make sense if say Norway and Denmark worked together against England while Scotland warred Norway, and met a army consisting of Norweigians and Danes, and the danes said "you know what ... we're not warring Scotland so we just sit here on the sideline watching you get killed, and not be big enough to complete our objective afterwards"

That's just wrong. If ally from war1 wants to help in war2 he should openly join the defender even if that's just temporary.
It's not restricted to something as simple as "enemy of my friend is my enemy" or "friend of my enemy is my enemy" in real life, and what's more important, it shouldn't be in a game either.

Of cause it is reasonable to want to help one's allies at times, but there should be a system that properly handles this.

By properly handles I mean:

1.AI considers the war balance. If the enemy is manageable by the ally himself, it may be not in one's best interest to waste one's troops on a dispute that only one's ally is interested in. (Although, by saving one's ally's troops, one saves some of one's own in the conflict that one signed up for.) On the other hand, if the enemy is too big it might be in one's interest to withdraw and forfeit the ally to his fate.

2.AI considers politics. If one is on good term's with one's ally's enemies, it may be not in one's best interest to meddle. Example. One helps neighbour1 to defend from neighbour2 because one doesn't want neigbour2 to gain power. Neigbour3 attacks neighbour1. Neighbour3 is one's closest ally and he is overwhelmingly stronger than neighbour1. In this scenario one could prefer neighbour3 to conquer neigbour1, because that saves troops (both one's own troops and neighbour3's troops as well) and keeps the allied land in allied hands.

3. Players have direct control on which wars to offer help in.

Generally speaking the "join war" system can (or should be able to) handle things well enough. (Would now be an appropriate time to mention that it doesn't allow us to withdraw from wars, but it should?)

The "Attach to army" function simply shouldn't be anything more than an order to follow and help with any common enemies. If a player or AI wants his troops to support an ally in any war, that should only be done explicitly and willingly. Currently this "WAD" look more like a loophole and/or an oversight than a feature.