transform tf frames without losing previous frames when new user come [closed]

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Hi, my question is can I transform all frames tracked by openni tracker without losing users while new user is tracked , for example if there is frame head_1 is detected and then new user come my code only transform head_2 and forget the first even if the user is not lost . Can I transform both of the frames .Thank you Here is the code , I just add the transformation of head_1 without other joints because the code is long ;

  string MAIN_FRAME_camera = "openni_depth_frame";
  string MAIN_FRAME = "torso_1";
  string FRAMES[] = {"head_", "neck_", "torso_", "left_shoulder_", "right_shoulder_", 
        "left_hand_", "right_hand_", "left_elbow_", "right_elbow_", "left_hip_",
        "right_hip_", "left_knee_", "right_knee_", "left_foot_", "right_foot_"};

  ros::NodeHandle node;

  tf::TransformListener listener;

  ros::Rate rate(30.0);

  ofstream myfile;
  ofstream myfile2;

  if( remove("/home/amal/catkin_ws/src/isr_activity_recognition/test_torso.txt") != 0 || remove("/home/amal/catkin_ws/src/isr_activity_recognition/test_camera.txt") != 0)
    perror( "Error deleting file" );
  else
    puts( "File successfully deleted" );
  char last_char;

  while (node.ok()){
  int contador = 0;    

    while(listener.frameExists("torso_1")==0 && listener.frameExists("torso_2")==0 && listener.frameExists("torso_3")==0 && listener.frameExists("torso_4")==0 && listener.frameExists("torso_5")==0 && listener.frameExists("torso_6")==0 && listener.frameExists("torso_7")==0){
      ros::Duration(0.1).sleep();
      ROS_INFO("Waiting..."); 
    }
    myfile.open("/home/amal/catkin_ws/src/isr_activity_recognition/test_torso.txt", ios::app);
    vector <string> ids;
    listener.getFrameStrings(ids);  

    //while(contador==0){
      //ros::Duration(0.5).sleep();
      //listener.getFrameStrings(ids);
      for(vector<string>::iterator i = ids.begin(); i < ids.end(); i++){
        string elem = *i;
        if (strstr(elem.c_str(),"torso_") != NULL){
          contador++;
          cout << "Numero de pessoas: " << contador <<endl;
          last_char = elem[elem.length()-1];

        }  

      }

    MAIN_FRAME = "torso_" + boost::lexical_cast<std::string>(int(last_char)-'0');
    cout << "MAIN_FRAME: " << MAIN_FRAME <<endl;

    //FRAMES[i] = FRAMES[i] + boost::lexical_cast<std::string>(contador);

    //ros::Duration(5).sleep();  
    tf::StampedTransform tf_head;

        try{
           ros::Duration timeout(1.0 / 30);
           listener.waitForTransform("torso_1", "openni_depth_frame", ros::Time(0), timeout );
        // head
        // torso
                listener.waitForTransform(MAIN_FRAME,FRAMES[0]+ boost::lexical_cast<std::string>(int(last_char)-'0'), ros::Time(0), timeout );
        listener.lookupTransform(MAIN_FRAME, FRAMES[0]+ boost::lexical_cast<std::string>(int(last_char)-'0'), ros::Time(0), tf_head);

        double x_head = tf_head.getOrigin().x();
        double y_head = tf_head.getOrigin().y();
        double z_head = tf_head.getOrigin().z();

        double roll_head, pitch_head, yaw_head ;
        tf_head.getBasis().getRPY(roll_head, pitch_head, yaw_head);
        tf::Quaternion q_head = tf_head.getRotation();