This has been asked before and sort of answered here with a workaround.
However I'm hoping that there is a more direct solution.
I need to use permission groups to restrict access to content for an extranet portal. I don't want group members to see who else is in the group - it's commercially-sensitive information.
The only options for 'Who can view the membership of the group?' are 'members' or 'everyone'. I need an extra option: 'owner' (which is available for 'edit group membership' - I'm slightly confused why this isn't also an option out of the box for 'view membership'...)
If anyone knows how to implement this across a site collection please let me know.
Alternatively if anyone has successfully implemented the linked workaround I'd be keen to see the code.
We're on SharePoint 2013 (hosted) in Office 365.