Substitution VBUND - How it works?

Hi guys,

I know that the field VBUND is not changeable after the document is posted. So I have to reverse all the documents with the field VBUND filled incorrectly.

But in the future to prevent this procedure I want to create a substitution to u201Ccopyu201D the value from VBUND in one item to other item in the same document (example: this could happens in F-03...). But with the standard way I canu2019t get this substitution ready. Can anyone give me tips how to do it?

Thanks in advance,

Penny