Been meaning to raise this for maybe a year! Hopefuly the screenshot describes it clearly:

Or here: https://www.dropbox.com/s/27w16gwd6v21ni7/MEP-GroupingProblem-1.jpg?dl=0
This is MEPP 2016. Haven't tried it in MEPP/2017 or whatever label it now has.
Terry, East Grinstead, UK