I am the Byz at about 1510 and have taken Greece, Anatolia, Armenia/Caucasus, the Levant and Egypt back along with a large swath of southern Russia colonized from the GH. Venice, Serbia, Wallachia and the Ukraine are my allied vassals. I sold the western Russian provinces back to Ukraine to get her to 8 provinces and kept the Eastern ones. I just obtained an alliance CB against Muscovy, she declared on Georgia (which she can't get to mind you as I completely surround Georgia but what the hey). So I am considering a blitz on central Russia but really don't want all those provinces as I will get the over-expansion penalties. Is there a down side to attacking Muscovy and handing over the provinces to the Ukraine, i.e. are there problems with very big vassals? A good 15-20 province Ukraine would do wonders in my eventual war against super-blob HRE Austria.