i.e. you see allies where they was like 1day ago, because you heard this from a messenger or something.
Honestly you shouldn't have to announce to the world who your alliances are. If people can't figure it out it's an advantage for you and your allies.
Also i didn't like in EU3 and CKII that you can't just declare war on someone. You want to know what my casus belli is? I want your fucking land, and my army is big enough to take it.