API Staging: how to test with FACe?

Hello,

I'd like to implement Spain B2G invoicing, sending and receiving invoices to/from FACe. First I'd like to manually cover the process by calling the respective API endpoints.

Is there a possibility to simulate/trigger acceptance/rejection/etc. of my issued invoices?
How could I simulate an incoming invoice from FACe?
What would you advise with regard to sender and receive/contact configuration in the invoice? Do you have prepared example invoices maybe?

Thank you in advance!
Tamas