Subgroups are a special type of cohort

Subgroups are defined by the identities of the individuals who belong to the cohort rather than by the criteria that select those individuals.

As a consequence, subgroups are not editable in the way that standard cohort definitions are editable, since all that Atmolytics has available to it are the IDs of the individuals in the subgroup rather than a set of criteria that can easily be applied back with Cohort discovery.