Within RM, you can create such a named group by marking persons in the Mark Group dialog of RootsMagic Explorer with the criteria:
Number of children equals 0 AND Number of sets of parents equals 0 AND Number of spouses equals 0However, as she connects, merges or deletes persons and because there are so many to begin with, she wishes that the group membership would be easily updated. It is pretty cumbersome to have to use RM's Edit Group functionality every time.
An alternative I suggested is to use Tools > Count Trees. Every unconnected person is a "Tree" with a count of 1 member. That's not terribly convenient because the list of trees is very long and is ordered in descending size, not by alphabetical or other sorting, and cannot be exploited as a Group can be by People View or any other report.
So I created another SQLite script that creates or maintains a group named "SQL: Unconnected Persons" and it's available for anyone to use without warranty of any kind at Group - Unconnected Persons.
And, once again, the plea goes out for the development of RootsMagic's Groups functionality to support the easy storing, editing and reapplication of a group's selection criteria.