I'm considering setting up an online invoicing service and I was wondering if it would be possible to make _one_ Joomla + invoice installation and for each Joomla user he or she (or their company) when they log in, they would only see their own invoices and not seeing other user's invoices and numbers?

Something like a webshop that has a multivendor option, only for this is for invoices/accounting.

Thanks,
Andreas