It seems to me that a parent group's membership is made up in the same way that a smart group's is, using civicrm_group_contact_cache. Altered the Utils class to look out for the group's children field - if this is truthy then it has children and therefore membership should be found from the cache table.
It seems to me that a parent group's membership is made up in the same way that a smart group's is, using
civicrm_group_contact_cache. Altered the Utils class to look out for the group'schildrenfield - if this is truthy then it has children and therefore membership should be found from the cache table.