Control position constraint object that already constraint to path



  1. I have first object (helper-1) that path constrainted to spline-1
  2. i have another object (camera) that path constrainted to another spline

what i want - i need to create helper-2 that would control position first object (helper-1) while it
will be following along its own path (spline-1) … then i will constraint this helper-2 to camera and do some animation when at some part of spline-1 my helper-1 moving by its own creative way and then smoothly follow camera.

question - how it possible to constrain 1 object (helper-1) to path(spline-1) and at the same time to helper(helper-2) ?