Add a one-time special service for events like Christmas or Easter. Check-Ins, Services, and Calendar all allow you to create new special events or add the time to your existing event, depending on what works best for you.
If your locations will be the same and only the times will change, modify the times of the regular event for the special service. If your locations are significantly different, or you want to track the data separately, create a new event with corresponding times and copied locations.
If you're tracking the special service with your regular services, you may need to add an additional time that matches the time of your special service.
Once the session from the week before has ended, navigate to the next session using the arrow.
Add the special service time to the next check-in, so people can check in to it when they arrive.
After the event is over, make sure you go to the next session and remove the additional service time!