Full proposal is at https://sourceware.org/glibc/wiki/Proposals/GroupMerging Short version: Many users would like to be able to use central LDAP systems like FreeIPA or Active Directory and be able to supplement local groups (such as 'wheel' or 'adm') with entries maintained on those central systems. To do this, we need to be able to merge group membership lists from one data source into others. Related downstream bug: https://bugzilla.redhat.com/show_bug.cgi?id=1146822