Vassals in aoh 3

[Barbaris 115]

The vassals in aoh 2 are very under-developed. Here are my suggestions on how they can work in part 3 of our game. Some of these suggestions are not mine, but I decided to systematize all the good suggestions here. 
1. The "offer vassalization" button. This button is not working properly at the moment. I didn't find this button in the alpha version, maybe I didn't notice it, maybe it's not there, but I think we need it, I think it's a good idea to voluntarily vassalize small states or tribes. But what is the point of countries becoming vassals?...
2...Investments and construction. In aoh 2 the vassal does not get anything from the suzerain, maybe only protection, but this is debatable. I suggest adding the opportunity to invest in vassals, build buildings and exchange technologies (probably not to exchange, but to give technology to a vassal). Therefore, it is sometimes advantageous for a small country to become a vassal, receive investments and development in return for tax (I know that many people have suggested this, but I couldn't help but write it). It is also necessary to give the bots the opportunity to ask to becoming a vassal, but so that this is rare, so that the entire map does not become divided into several spheres of influence. Also, the vassal himself can invest, build, but this is more the duty of the suzerain.
3. Control over the army. Many people also suggested it. You can call up an army in the provinces of a vassal and control it. (Here, in my opinion, it is debatable, because then the vassal becomes too dependent on the suzerain. Maybe in order to give him at least a little freedom, you can simply request military assistance from him and he will call up the army himself and put it under your command).
4. Foreign policy. In aoh 2 the vassals themselves can start a war without your consent and you either intercede or he will be captured. In the new game, let the vassals not start a war without the permission of the overlord. Also, vassals should not give the right of passage of troops to other countries without your permission (I'm not sure if this is now, but let it be here). In other aspects, the vassals will be in charge of foreign policy themselves. Oh, yes, I wanted to say that the vassals of one suzerain should have good relations with each other and good relations with the allies of the suzerain. 
5. Integration of the vassal into the suzerain. Right now, we can only attach a vassal with an ultimatum. But it would be great if the vassal could be joined peacefully (I don't know how to implement this better, maybe your relationship with the vassal should be excellent, or you should invest a lot in him so that he becomes very dependent on the suzerain, maybe come up with a scale of dependence, there are many options, you can offer). Thus, the vassal will become an autonomy (I also wrote about the concept of autonomies in a separate post, take a look). 
6. The desire for independence. The vassal, as in Part 2 of the game, will strive for independence under certain conditions. For example, if there is a political crisis in your country or you are losing a war. Vassals may also seek independence if you don't develop them or if you don't protect them. 
7. Vassal levels. This was suggested here. The ideas ranged from several types of vassals, to several dozen different types with economic, political and historical features. I like the option where there are 3 types of vassals: a dependent country (pays tribute, gives the right of passage of troops), a classic vassal (whom I described here) and autonomy, which I have already written about.
8. Ideology. You must manage the ideology of the vassal yourself. This is what we all wanted and are waiting for in aoh 3.
That's all, if you have any interesting suggestions, then write them in the comments