Create invoice from 3rd party application
I'm handling our Member billing from 3rd party custom application because we need to enable our customers to pay in 1,3,6 or 12 months. Now everything is going fine, I'm letting customers also pay to the counter by cash,sport cheques or credit card or then by bank transfer or web payment from the third party application. Payments to the RGP I check from the RGP DB automatically.
I now realized I can also create the invoice to RGP so I can include it in the POS to customers invoice.
Is there anything special to keep in mind when adding to Invoice DB or is there API for doing inserts?
Do I get alerts at check-in if the invoice is due by X-days?