invoice grouping

I would like to set up a monthly grouping of invoice to editing him on customer's number by transport and AVEX.

This treatment will be run by a job.

A new message will be create for that purpose and I think that a new form of invoice will be creating.

I ask the question to know if such a document (which will be send to the customer) can legally replace the standard invoice.

Anybody has already do such a treatment and how?

Thanks

Danièle