Mark booking as completed after...

If someone is absent I want to put it as "no show" after 15 min of being late. Thats not possible right now because I would have to wait for the complete hpur of that meeting to end and then wait 5 more minutes to put it as "no show". I would like to be able to put it as "no show" even if the appointment hasnt finished because then I can put it as no show and continue my day with other tasks and not thinking on when to go back to booking and put the "no show". Thats important for me because that determines the automation that occurs on fluent CRM when they complete the appointment or the have the "no show".