How to add items in Manufacturing process plan Workbench

Hi Folks,

I'm working on Manufacturing process plan in Aras innovator version 11 SP12.  I would like to add other items,  which have a relationship with operations, in the workbench to select, drag and drop the items into the operation. I tried to modify the method: 'mpp_GetWorkbenchGridHeader' as shown in below picture. but it didn't work? how i can do to add other items along with machines,tools etc. In my case, other items are OperationList, MachineModels as shown in the below image.



Venkat Sai