Giancarlo Stanton (left knee), Logan Morrison (right knee) and Greg Dobbs (left hamstring) were examined by team physicians on Tuesday.
"The doctor said to go ahead and start baseball activities," manager Ozzie Guillen said. "We're going to start them [designated hitting] in a few days. We'll sit down with the coaches and see how we're going to make it work. Obviously, it's going to be Minor League at-bats. For now, they will be the DH."
All three have been given the green light to start light running. Stanton is regarded as a little more behind the other two.
The Marlins are off on Wednesday, and the players will get another day to rest before beginning activities on Thursday.
"Stanton is going to be a little bit slower, but everyone is going to do baseball activities," Guillen said. "They'll run a little bit."