What's the ultimate goal? Merely adding another group to the user or to
add the group address to the user? Assuming it's the latter, then you
may skip adding the group, simply just add the Public Folder email
to the selected users.
Anyway, I may extend the auth_data array with the groups, if it's the
more elegant and effective solution to your problem.
Since I don't have the Public folder/Distribution-group addresses in
Active Directory (but in O365 only) it's easy to add a group on Piler
and attach the Public folder address there.
Then in Active Directory I would add users to a group which represents
this public folder. If that group could be added to the Piler user
session, that would be perfect.
But I don't want you to build something that's only useful to me :D
I was just curious where the group information in Piler derives from and
if I could leverage that myself.