- A reference guide and manual in Russian for Heroes 3.

So, you're saying that this is quite possible? That, by using the "clairvoyance" spell or thieves, for example, and seeing them flee, monsters can still join, but only after they reproduce, right?
I think we need to refine this question a bit and add it to the physics engine.
P.S. I've been playing Heroes 3 for a very long time, but I've never encountered this, not once...

It doesn't necessarily have to be after they reproduce; you can simply weaken your army, i.e., shift the balance of power in their favor. But this is only done to prevent them from fleeing and to prepare them for a fight... However, the question of joining is independent of this; you still need to increase this probability, for example, by recruiting the same units into your army... This is what we were talking about earlier. Simply weakening your army won't allow you to recruit them... Conversely, if the probability of joining is high enough, then when the army is weakened, the neutrals will join instead of fleeing... But I will still make a small caveat - diplomacy involves the concept of probability. It is practically impossible to calculate it experimentally. Therefore, it is possible that there are still some interrelationships - and we don't know everything about them... But I have had cases where, instead of fleeing, the neutrals subsequently joined. But I can't say for sure what exactly this depended on... You just need to test this for a long time.