In the event that a party shows up with more than the expected amount of guests (e.g. 6 guests arrive for a 4-top reservation), you are not obligated to seat the extra guests. The decision is entirely at your discretion - however, if you choose to accommodate them, you will be credited and paid for all the extra guests seated, even if it puts you over your daily seat commitment.
You will report the final guest count in the "Party Size" field when you complete the reservation in the Avvail dashboard at the end of the shift.
For step-by-step instructions on how to complete a reservation, refer to this support article.