Returning uncollected pieces to starting point without stopping conveyor

Hello,

 

I am building a production line (pick and place) using a 4-5 pickers. All uncollected pieces must return to their starting point using a conveyors and they have to go again through the pickers with alongside newly created items. The main conveyor must be running all the time.

I tried to use conveyors and take uncollected items back to the starting point just after the feeder but it stops the head conveyor. This cant be happen.

After that I tried to use conveyors and take uncollected items back to the starting point just before the feeder but returning items disappear in the feeder.

 

So, how do I do it correctly?