Any tips on how to indirectly undermine an ally kingdom?

Hello, i would like some tips on how to undermine a friendly kingdom without damaging my relations with them.

To put into context (wall text): im a vassal of Kingdom of Rhodoks, and through the course of 3 months, the war with the Kingdom of Swadia raged on, while we attacked them from the south, the Nords attacked them from the north, the Swadians lost the majority of their territorry, only Praven and a couple castles remain. We took Uxkhal, while the Nords took Suno and Dhirim, in the following weeks a defensive pact was formed between out two kingdoms. But shortly after, the Nords declared a truce with the Swadians, and turned their eyes east to their war with the Vaegirs. The Vaegirs, who were already getting their asses kicked by the Khanate, lost Rivacheg, Curraw, Reyvadin and several castles to the Nords. (RIP Vaegirs, all they have now is 2 castles and 2 villages).

As it stands now, the Kingdom of the Nords controls 8 different cities and almost 1/3 of Calradia. There is no immediate danger at the moment, the defensive pact still on and my kingdom is busy erradicating the crumbling Swadians and holding back the Sarranid who recently declared war on us.

But when the day comes when the Rhodoks and Nords go to war, i dont want to have to deal with a such powerful kingdom, i would like to know how do i turn the other kingdoms against them, how can i weaken the Nords without making them realise i am doing it?

Thanks in advance

Submitted October 30, 2018 at 06:45PM by Kugelschreiber16 https://ift.tt/2SxBO8M