CK II - Enemy has allies in another war, but all attack me

[Richard V III]

One line summary of your issue
Enemy has allies in another war, but all attack me

Game Version
Current

What expansions do you have installed?
All of the above

Do you have mods enabled?
No

Please explain your issue is in as much detail as possible.
Vassal has declared holy war against enemy. Enemy has defenders join on their side, including one of my tributaries. I declare a war on the same target. Defenders are not in my war. Troops attack my troops.

Steps to reproduce the issue.
Have a vassal declare a war on an infidel, have others join to defend the infidel, and then you yourself declare a war as the top liege on the same target

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[Richard V III]

I was getting an error message while trying to post this saying "use less than 100 characters," but it didn't say where to use less than 100 characters. I wanted to elaborate more, but was checking around which category had too many words, and accidentally submitted this.

My vassal declared a holy war on a target. The target gained allied units in the war because they were defending their faith. I declared a holy war for the same target. The extra defenders did not join my war. Their troops were grey until they linked up with the main target's army. They were then able to attack me with all of the troops instead of only the defender who was the only person in the war with me.