Invoicing buckets allows to group projects that needs to be invoiced in a single invoice however, it does not have ability to capture any additional information related to the invoice e.g. Case Code, Contact person - if it is different for each bucket etc.
Most Invoice Processing team would have requirements to identify which department, WBS or Case Code the invoice should be charged to for accouting purposes. Having a few additional fields that are either reflected in the invoice itself and/or the email that goes to the central email will allow to process and account for invoices effectively.
This will be worked on following invoice separation using attribution groups