Multiple service selection & buffer time flexibility

Before & after a client's appointment the staff member needs a buffer time to make preparations. The problem is that when a client chooses to have multiple services, the buffer time is automatically added in-between the services. So it makes the client unable to book the second service right after the first one. Would be perfect to have the option to add buffer time before and after a booking (not a service; the booking can consist of multiple services). So the staff member would have buffer time before the client's appointment, then complete the two services, and then have another buffer time after the client leaves and before the next client.