The arrests came one day after police dropped capital murder charges against Bruce Rogers, who was arrested Wednesday. He remains jailed in connection with an unrelated robbery.
Forrester, 17, was an honors student and member of the swim team at Southwest High School.
He and his sister had gone home for lunch on Monday when they encountered two intruders inside their home, police said. The sister ran out the back door but Forrester was shot in the head and later died at the hospital.
The teenage suspects, whose names were not released because of their age, were taken to the Tarrant Juvenile Detention Facility.
Rogers remains a "person of interest" in the murder investigation, police said following the teenagers' arrests.