How do I approve second stage requests to be added directly to the attending list?

Hello, 

I'm the second stage approver for event bookings. Each time I approve a user request via the notifications, the user is added to the waiting list and then I have to manually move them to the attending list. They also recieve a waiting list email, regardless of if a waiting list is set-up or not. 

I tried selecting ‘book user' via the user profile, but this doesn't work. I assume as they have already requested to attend an event and the first stage approver has accepted. I don't want to switch off the waiting list notification, as I use this feature for users who are staying on the waiting list.

Is there another option?