Hi acquario, welcome to the forums!
I'm sorry, but i'm not really sure what it is you are asking. Are you asking whether it would be possible to cede planets to other Empires?
If this is the case, then the diplomacy is still a bit of an unknown. We're not entirely sure what Mike plans for diplomacy and what will actually be possible (Since these may be different things). If you were to cede something to another Empire though, it would have to be an entire system, not just a single planet though, because systems work as a whole and it's not possible to split planets.
I know you only used them as an example as well, but there are currently no formal plans to include the Marquis in the game. They are not a "minor race" as such. We'll try to find a way to squeeze them in if we can though, for example, it may be possible to create Random Events based on the Maquis, such as a Maquis uprising in some of your outer colonies, for instance. But again, that was just an example. We don't yet know precisely what will be possible with the Random Events system yet.
