APIs or FBDIs for updating approved purchase order lines

Summary:

Confirmation of whether there is any way to change/update purchase order line details via external applications

Content (required):

There is quite a lot of information on this on CCC, but some seems contradictory.

My question is whether any method exists to update approved purchase order lines. The requirement is to integrate these amendments from an external application. At this stage the method Rest/SOAP/FBDI is not really important. Just want to understand if it is possible in any way.

Version (include the version you are using, if applicable):

21c

Code Snippet (add any code snippets that support your topic, if applicable):