Punchout inventory items

Summary:

Requirement is to use Punch out which will return the price for inventory items

Content (required):

The customer has many inventory items that they purchase from suppliers having punchout capability in addition to expense items as well

The customer doesnt maintain any pricing related to the items.

Requirement is when the punchout is used , supplier returns both inventory and expense items with price details. For the inventory items we need to map it to our internal item numbers so that it can be received into the internal inv org, expense items remain as is....

Can someone confirm

1) Is it mandatory to setup an agreement with the item numbers and update whenever a new inventory item is created