My 14yr old daughter has osteochondromatosis, active in sports, hard time stretching legs, lumps side of knees, do u suggest therapy?

Physical therapy. Physical therapy may provide stretching exercises that help osteochondromatosis. However surgical procedures are often needed too.
See pediatric ortho. Followinh amf removing bumps can solve problems with tendon rubbing therapy can't shrink the bumps follow enlargimg painful ones cases of malignamt transformations have occured.