There are two workarounds for this.
1. Move just a piece of a reservation. You can modify the checkout date to today, proceed to check out the reservation, and create a new one for the remaining days in the desired site.
You will need to follow the steps in Getting Started with RoverPass - Minute 14:09.
Or
2. Move the previous reservation to another site.
For this, you can check your Site Availability Grid report located in your Reports tab. This report provides enhanced visibility into both historic and upcoming reservations.

Then sort by reservation check/checkout date and Site number.

Once you locate the reservation, click on the Modify Reservation tab and change the site for it. Repeat this process for any other reservations that overlap during the dates.
