What was Roosevelt supposed to do about the Soviet occupation of Eastern Europe in February 1945?
The Red Army took Lemberg/Lwow/Lvov/Lviv in June 1944! They were on the Vistula line by August 1944. Army Group Center had been destroyed in Operation Bagration.
Two weeks before Yalta, the Red Army occupied Warsaw, and deployed 163 divisions, 4500 tanks, 13 600 artillery pieces, and 5000 aircraft in the most formidable array of combat power ever seen in the history of the world before or since.
IF something was to be done about postwar arrangements (other than the fait accompli ratified at Yalta), it should have been done by January 1943 at the latest.
Once the Sixth Army surrendered at Stalingrad, the course of European history east of the Oder was set in stone.
It's Lwów!