Another war with Belgium - bug?

[doomtrader]

I'm playing as a central powers and in 10th turn Belgium is already conquered.
However I've realized that there is a possibility to declare war against Belgium. Why?

[FOARP]

Actually this happens for all countries. Basically, even if you entirely conquer a country, when they surrender they still theoretically exist as a government-in-exile even if they have no cities/units on the map. Unless the allies liberate them in the meantime, declaring war on Belgium when playing as the Central Power after you have entirely occupied their country and they have surrendered will just result in them surrendering again.

Of course, ideally a more complex diplomatic model would allow the allies to liberate Belgium as an independent state once they recapture Brussels, with Belgium re-joining the allies. Also, it would allow the Central Powers to establish a client government in the territory after they have entirely conquered them, meaning they join the Central Powers, but with heavy penalties for PP/AP/MP.