Recreating Warranty Contract for item already shipped to the customer via a Sales Order

We have an item which did NOT have a Warranty item attached to its BOM at the time it was received into Inventory via a PO and subsequently shipped to the customer via a Sales Order. Hence no Warranty contract was automatically created.
Is it possible to get the Warranty re-created by the system somehow? If yes, what options do we have, and what is the preferred method?

Thanks in advance for your help.

Regards,
Varun.