How to restrict the condition type in PO (Addition/Deletion)

Dear MM Experts ,

My client business scenario is created release order with ref to contract .

In contact having price conditions (both header and item) will automatically flow to release order and price value should be in display mode .

Further no more going to conditions addition/deletion in Release order.

Contract ME31K.

Release order:ME21N.

I had made as condition type "Not able to process manually ",but it will effecting all PO document types .

I want it will work for only selected PO document type (Release order document type )

Please suggest me it will possible customization or i can go for ABAP help required .

if it is possible in programming please give me suitable exit/badi name .