Pergamon repeatedly destroyed by Ptolemaic assassins

Hello everybody and thank you for a wonderful mod. I'm writing to point out a single annoyance I've been coming across - nothing to spoil the game or anything, but just, yeah, annoying. In several campaigns of mine - as Seleucids, Macedon, KH, etc., I have repeatedly experienced Pergamon being wiped out by the Ptolemies assassinating all their PM's. I find this a little gamebreaking, because Pergamon is a new faction and I'm so excited to have it in the game at all - I usually ally with it rather than fight it. I was thinking if it would be possible to solve this - perhaps simply by the two factions not actually starting out at war with each other (they don't even share a border to begin with). As Macedon etc. I have had to either send my own assassins to their towns and kill off the Egyptian ones as they turned up, or to ally first with Pergamon and then with Ptolemies, to make them ceasefire - but then if I want to make war with Egypt, I have to break an alliance which hurts my reputation.

There was another thread on here complaining of too many assassins - but that was for the player him/herself. I can fight off assassins if I want, I wouldn't mind that. But it annoys me having to do it on behalf of Pergamon, just to keep them alive as a faction, because it means spending time doing something which I don't actually feel my faction would "really be doing" in the in-game universe (I mean, the Antigonid kings wouldn't care if the Attalids died out, but I as a player work to keep them alive to have a challenge later on... but then I can no longer immerse myself in the idea of being an Antigonid while playing)