Member Check-in System

I’m trying to create a member check-in system. I have a rough UI created in the screenshot below. I want to be able to select multiple members to check in at once using the checkboxes to the right of their name. Then, once I click on the “Check in” button, it adds their name to the list of members that are checked in for that particular day. Finally, it will also change the status tag at the bottom from “checked out” to “checked in/here.” Ideally, it would also show the date of their last visit.

How can I have a “select all” to select the checkbox of all visible members in the list?

What would be the best workflow for the “Check in” button? I’m having trouble thinking if I should have a data set with dates and then append each username to the field or should I have a “check in” column in the user data and add append a date stamp to that column each time they check in?