I think you got it, but just the other way around, actually. The members documents exist so we can search user/group memberships, and memberships documents exist so we can search a group's members.

This isn't done in the producers because members/memberships are indexed independently from the resource document -- this means that when someone updates a group or adds a member, we don't have to update *everything*.

There is a parent child relationship from the resource doc to its members doc and memberships doc. Documentation on this is in the `createResourceMembersSchema` and `createResourceMembershipsSchema` methods of `oae-search/lib/init.js`.

Probably better in confluence, though.