Hi Ramon,
Yes, I was able to achieve the solution that I sought, but the only thing that I didn't perform is to assign numbering series for Business Partner and Item Master Data. Though my client was diligent enough to take the responsibility to control that assignment of each master data to its respective business units. What I did, since the business units was maintained in one company database I maintained a Segmented Chart of accounts, numbering series was setup per business unit, Item Master Data was allocated to it's respective default warehouse and Business Partner Data was sorted per business unit through an UDF since the customer and vendor group was used to another function. The generation of reports was restricted to the users, so all reports was hidden except for those who are authorized, users request reports indicating the parameters.
Regarding on generating of separate invoice per business unit, I make use of the User Defaults where you can allocate the business unit per user, since the invoice format are the same across business units It has only one format and default to all business units.
Best Regards,
Zeus