A Purchase Order (PO) has already been created in the system

Summary:

A Purchase Order (PO) has already been created in the system, and an invoice has been raised for half of the amount. Initially, this PO did not include any project details. However, we now want to associate project details with this PO through a change order. When we attempted to do so, the field for entering project details is not enabled.

Or Is there any way we can get commitment against existing PO which does not contain Project details

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