Hi Marisol:
I reached out to Sharon Horton for guidance regarding your questions. Noted below is the feedback she provided:
"This is a very complex topic and it can't be easily answered within the confines of an Exchange post. However, we would recommend that you go to this web site which contains a large number of free webinars that have been conducted by our experts in the Best Practice Center. The Webinar that you should look for is Amendment Processing and Advanced Approvals."
Hopefully, this will get you started.
Regards,
Debbie Curtis-Magley
Ariba Exchange Community Manager