We need to assign staff to shifts. I have a calendar of shifts and can put two staff members on a shift. I want to have the staff confirm that they will do the shift, sort of like inviting them for an event on Google Calendars. 

I think Interface might be the place to do it. I was looking at using Button and having it change the staff person's name from "Sue?" to "Sue Yes" or something like that. However, with the Set option, I can't have the staff person change just their name but rather changes the whole field. I need to get permission from both assigned staff.

Is there a way to make this work?

Thanks.