I don't know if this aspect has a history or not, but it will be very useful in modding
That a subject is controlled by two or more overlords
Create some kind of subject or free the possibility that instead of one overlord, two or more countries can interfere in the internal affairs of that country.
It will be wonderful, a lot can be maneuvered on this issue
Or
the influence of each overlord can be determined individually or by decisions
And whichever Overlord has the most influence can do the most with that subject
That a subject is controlled by two or more overlords
Create some kind of subject or free the possibility that instead of one overlord, two or more countries can interfere in the internal affairs of that country.
It will be wonderful, a lot can be maneuvered on this issue
Or
the influence of each overlord can be determined individually or by decisions
And whichever Overlord has the most influence can do the most with that subject