Our website http://www.performanceconsultants.com uses a child theme based on Discovery. I have just added a 4th level of menu to our Primary Menu. The 1st level is visible in the menu bar at the top. When you hover over that, eg 'What We Do' the 2nd level drops down. When you hover over 'Wider Organization' the 3rd level flies out (there is no further level on this item). However, when you hover over 'Leaders & Managers' or 'Individuals, Coaches, Trainers' the 2nd and 3rd level menus fly out at the same time.
So, it looks like coming out of 'Qualifications & Certification' is one long list. In fact there are 3 items in that 4th level menu but the 3rd item is hidden by the 'Coaching for Performance Level 1 - Foundation' which is in fact the 1st item in the 4th level menu coming from 'Public Workshops'.
Many thanks for your help. I have enabled support access should you need it.