James, Tim
Now I remembered that many years ago I had downloaded an American software to do invoices.
The author later wanted to translate it into Italian even after my exhortations and from other Italians.
So I myself helped translate it into Italian:
translating it into Italian all procedures had to comply with Italian goverment rules
I don't know if the program works in a network but I could try
but right for you to see the difference between the American and Italian systems
For customers, it removed the customer code before it was there
But interesting to see the creation of invoices with the invoice number
already in the screen of the new insertion and not after the registration as you say and wrote
I suggest you install the English version first and then the Italian one in another folder
The author is American
Legal Department
NCH Software, Inc.
6120 Greenwood Plaza Blvd
Greenwood Village CO, 80111
USA
the software is free and can be found on this site
https://www.nchsoftware.com/invoice
there are also the snapshot ( see the invoice addnew)