OpenGL >> Adding branches to skeletal joints

OpenGL OpenGL: Basic Coding
1

Hi, I’m new to openGL, I need some help in understanding how to allow users to interactively add branches (bones) to already-existing joints of a skeleton. The joints in my program now is already in the form of a recursive joint hierarchy (refer to code below):

void display(void)
{

    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();
    glColor3f(1.0, 0.0, 1.0);
    root();
    glColor3f(1.0, 0.0, 0.0);
    glTranslatef(0.0, ROOT_HEIGHT, 0.0);
    shoulder();
    glColor3f(0.0, 1.0, 0.0);
    glTranslatef(0.0, SHOULDER_HEIGHT, 0.0);
    elbow();
    glColor3f(0.0, 0.0, 1.0);
    glTranslatef(0.0, ELBOW_HEIGHT, 0.0);
    wrist();
    glFlush();
    glutSwapBuffers();
}

I’m not sure how exactly to allow the user to choose and attach a new bone to a joint. Any suggestions are much appreciated, thanks!