If you view the calendar, you are able to see at a monthly view the fields that are available.  You will see the "home" team listed as A1_A2, meaning that those are the only age groups that can play on that field.  Hopefully you're able to figure it out.  Once you and the other manager have settled on a date, there is a "form" that you can fill out on that website and after submitting the form, an email is automatically sent to me with your request.  Once I review your request, I will make the change on the website as well as remove that game from the field availability.