The Philadelphia Phillies activated Feliz from the 15-day disabled list on Wednesday.
Feliz, who was battling a bulging disk in his lower back, was placed on the disabled list on July 29. He was sent on a rehabilitation assignment on Sunday, and hit two home runs that day for Double-A Reading.
The Phillies activated Seanez from the disabled list on Saturday, and sent third baseman Mike Cervenak to Triple-A Lehigh Valley, according to the team's official Web site.
Seanez had been out with an inflamed right shoulder, but returned before Saturday's game after two rehab outings with Lehigh Valley and Class A Lakewood, respectively. Seanez, who is 4-3 with a 3.58 ERA in 31 relief appearances for the Phillies, is expected to help lighten the workload of Chad Durbin, who has appeared in a career-high 51 games.