Marketpress with Appointments +

I am currently using appointments + on a clients website and want to integrate marketpress so that the user can book multiple appointments and only make one payment. I have set up the calendars on each users individual buddypress profile page and have successfully gotten that to work the problem I'm now having is getting the marketpress plugin to put an "add to cart" button where the paypal button currently is. Not sure if I'm being very clear. The website is tritutor.com. When a logged in user selects the appointment it provides another menu below the calendar that asks to confirm the appointment and once the confirmation is selected the paypal button shows up. I have tried to put the add to cart button there but it ends up putting it right under the calendar before the user selects the appointment. Thank you