Hi Sarah,
wich version is your SAP Business One?
It's simple:
1. Recive the Order with a B1 Obect (method #Synchronous Retrieval), the retrieval mode must be ExportImportMode
2. Change / put the comment data in the Comment-tag with xsl-transformation
3. Use a B1 Obect to update the order: the method must be updateDocWithSubDeletion and your payload the atom where you change the comment tag, like #atom1
Like in this picture:
