The Brewers made the moves before playing Pittsburgh on Sunday.
Schafer strained his right hamstring while stretching in the on-deck circle prior to a pinch hitting appearance Thursday against the Pirates. The move was made retroactive to April 18.
''They needed guys, and I wasn't going to be able to go in the next few days,'' Schafer said. ''It was the move that had to be made.''
The 27-year-old Schafer was hitting .214 with four doubles and two RBIs in 10 games.
Overbay and wife Sarah welcomed their fifth son, Eddie Christian Overbay, on Thursday.