When a customer has a part (such as an oil filter) that part may need to be special ordered.  To save time by having to order that part, the Substitute Similar Part feature can be used.  

A dealer is able to decide if a similar part needs to be added to any other part, even if that part is not in inventory.  

Click on Inventory Management 

Search for the part number you want to add a similar part for, then go into the part number detail page.  Click Similar Parts from the left hand menu 


Search for the part that will be listed as similar. 

Click OK to confirm that the similar will be added as an option for the existing part number 

The Part number now shows as Similar.