So re-formatted question. We are looking at Accounting. What I don't see at first glance is the ability to charge a customer for an invoice.
https://developer.sage.com/accounting/guides/concepts/invoicing/
I see in the API where I can create customers and invoices and invoice lines. In zoho I can make an API call to bill the customer. Does Sage do the same? (not seeing it at first glance).