Hi bunnyhabit. Thank you for your reply.
The members won't be anonymous per se; they would still be visible to Admin, who will be able to kick them out of the group at anytime if they cause issues.
Also, their posts won't be visible to anybody except Admin. Hence, it is pointless to spam post, or do anything that may disrupt the group since Admin will be the only one to see this, and would be able to kick them if they do this.
The reason this is needed is because my Aunt wants to run for elections, and she wants to know and interact with her supporters directly through this group.
However, as you are aware, supporters usually don't want to reveal their identity or be known to each other.
Therefore, if it is possible to create a group (or something similar) where supporters can join without them being visible to each other, but visible to my Aunt (the Admin), it would be of great help.
Also, I have checked on the AppStore and GooglePlay. There does not seem to be any app that supports this type of "group".
Once again, thank you for your reply.