Here's what I do in RoA2: All AI nations have relations with each other set to -100 by default, and a pool of 'potential allies' are then picked with relations 50-100. By reducing the number of allies the AI can have, I reduce the chance of a cascading alliance and can address common problem areas (like greek states all allying each other).
I've been thinking about restricting this even further and making it so the AI is only permitted to ally each other by event, giving me complete control over who allies who so I can completely eliminate the problem.
I've been thinking about restricting this even further and making it so the AI is only permitted to ally each other by event, giving me complete control over who allies who so I can completely eliminate the problem.