Add pdf invoice to WordPress booking site -- 2

Hi, I need to add a pdf invoice to a wordpress website. The website uses this plugin: [login to view URL] Website: [login to view URL] Currently it does this: - When customer makes booking request, it sends 1 email "Thank you for request". - When admin accept the booking, sends email with text "Thanks for booking". I want this: - When customer makes booking request - it sends 1 email "Thank you for request". - When admin accept the booking, send same email but with a pdf invoice of 20%. - When admin see that it has been paid, there should be a button 'Confirm payment' and then a email is sent "Thank you for payment, here are mor info..." and a invoice with 80% is sent. So in total, you just need to create the system to create 2 invoices.