The Visit Duration Line Item on Services allows you to pick how you are billing the client and paying the staff based on the time spent during a service. 

Although you cannot change what was already logged as check-in and check-out, you can definitely use the time reported by staff after the service or add a custom time if the staff sent you their actual times via chat or message outside of the app.

We will keep the actual check-in and check-out for the records but you can definitely choose these options to customise the visit duration.