quantity only work center

I am trying to create a work center that only has quantities go through it. That is, to have P311221 log employee #, shift, operation, work order. 

Doing so moves the quantity to the next work center operation status. 

I have setup 2 work centers with pay code '0' . and I am able to post just quantities through using P311221.  

My problem is when I run superbackflush to charge labor for the remaining 2 work centers, Its adding transactions to F31122 and in P31226 i see negative quantities at the first two work centers