Problem & Request: Summary Function - ability to edit the range contained in the summary

When I use the Summary function to place a Bracket around a set of a larger set of entries - if I change the underlying hierarchy of entries (i.e. add another at the end) - it goes INSIDE the Brackets.  Rather than outside.  There ought to be a way to change the RANGE of entries, after a Summary Bracket has been placed, to expand or contract the number of entries contained within its scope.