You are able to add multiple billing items while creating an Encounter for a patient:
Scroll to the Billing Items Section of the Encounter and click on either the "Add Private Billing" or "Insured Billing" button on the right hand side.
Selecting "Private Billing"
This will allow you to enter the billing information.
You can select the billing Practitioner, search for the billing code or alternatively the description of the service, and add corresponding diagnostic codes.
Selecting "Insured Billing"
This allows you to enter the billing information.
You can enter the billing code/ description, corresponding diagnostic codes, the service location, and what type of claim it is at the bottom.
To add another bill, click on the "Insured Billing" button again.