Multiple devices can be used by different administrators at the same time to check members in or out. To make sure your particular sheet is up to date, or to refresh your sheet after another administrator has made changes, simply:
1) Click the 'back' arrow to return to the 'Check-In/Out Sheets' page
2) Select the appropriate list to re-open it.
This will refresh the sheet so that it reflects the most up to date information regarding member statuses.