devil said:
Especially if people are going to break vassalisation from me every 5 years... But to be fair all( if any ) that are vassalised by me in the endgame, Now just a friendly warning. I expect all to act as loyal vassals and do what I say and fight who I say, without holding back. If I find you betraying me ( like forzaa did in mach2) you will have all your forces disbanded, and have the most boring endgame ever.
Now, that's a real France

. Bloodthursty and dangerous!
Seriously, all should read the rules regarding vassalisation and honour them. The rules say:
"If one player is vassalized by another, he is expected to act like one
After five years, a vassal may choose to fight for independence, but must---
-Break vassalization
-Declare war"
So breaking vassalisation is clear: month X break vassalisation, month X+1 DOW your former overlord.
To avoid possible misunderstandings and problems during the game, perhaps we should now talk about how exactly a vassal "...is expected to act".
I remember very clearly the discussion on the topic. Between other things, disarmament to a certain level was mentioned. I suppose also some control over treasury. Perhaps the best would be the overlord to check how many diplomats his vassal has and order him to use them only to contact with his overlord...
Perhaps a vassal overlord can demmand a vassal to participate in his wars...
But there also has to be some limit. A vassal and his overlord should somehow set this limit so that both will know what will happen in 5 years. If the overlord is not pressing his vassal too much perhaps nothing will change so fast... But if he is demmanding a vassal to attack with the full force his yesterdays allies, the overlord should know first day in the 6th year the vassal is lost.