Nope, part of Polish territory. After all, Poland owned whole Belarus and lion's share of Ukraine pre-1795. So, they'll just grab as much as they can. Bot Polish government supporting Inependent Belarus strikes me as something much more ASBish than Lenin building libertarian society along the lines of Ayn Rand teaching or Hitler turning Philosemitic.Poland becomes asbish strong and beat the crap out of the bolsheviks. Belarus and Ukraine become Polish puppets.
Well, Second Polish Republic was as much "Commonwealth" as Polish society of the day was willing to allow.There were a lot of Polish generals who tried to create a Commonwealth of nations under Polish control.