We purchase vulcanized conveyor belts which are first shipped to us for fitting and then we ship the belts back to the vendor for the final splice, then they are returned to us.  So, we receive the belts twice.
 
We are invoiced twice, once for the total cost of the belt (all splices & shipping), and then just for the shipping for the final splice.  
 
My question is:  How can I track the final splice?  I thought of adding a dummy item, type N, w/ no cost to the PO.  But if we received the item it would show up on RNI.  Does anyone have a good solution?

Michael is on the right track.  I would have a type R part for the first receipt and a type M for the second which has $0 cost and a BOM of the type R.  The first PO for the Type R would reflect the total costs and the second PO would be for $0 but could be received and invoiced for the shipping costs and to close it out.  The second PO being for the Type M part would consume the type R and roll the cost into the type M.

You need to add one new part number - the spliced belt, type M.  Edit the BOM of the next level subassembly to call for this new part instead of the old type R belt.  Then give the new type M part a BOM of 1 each of the original type R belt.
 
Try it in a test company so you can see how it all flows.

Thanks again for all the help!  I understand what everyone is saying, but without going into great detail, I think it would cause more problems & confusion for us.  Although, I'll keep the type M process in mind for future reference.