Good question! There is not yet a tool that lets Hipcampers specify that there will be more or less people joining one one night of their trip vs another night.
Our recommendation is to have the Hipcamper select the group size that reflects the maximum number of people who will be in the group at one time and then make a plan with you as their Host to get the correct refund for the days where they had less people in their group. You have the ability to refund this amount from your calendar after their trip ends.
Our Support Team is here to help with any refunds that need to be processed in this way if you need assistance. You can file a support ticket and we can help with getting it squared away.