I hate it too, but I just conscript a large stack to counter theirs and use my original stack for the original plan
You have a huge stack of people ready to invade your neighbor to the south and right before you declare war your neighbor from the north backstabs and declares war on you?
You have a huge stack of people ready to invade your neighbor to the south and right before you declare war your neighbor from the north backstabs and declares war on you?
You have a huge stack of people ready to invade your neighbor to the south and right before you declare war your neighbor from the north backstabs and declares war on you?