How to mass update shipping method on the PO header?

Summary:

We'd like to update the shipping method field on the PO header. I know FBDI and VBCS templates don't work, but is there any ways else to fulfill this request?

Content (required):

We'd like to update the shipping method field on the PO header. I know FBDI and VBCS templates don't work, but is there any ways else to fulfill this request? For example, REST API? Web Service?

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