Hi!
I had the same issue and found that it can be solved with an Address Book thanks to this other topic: Address Book New Group problem
To sum it up, we can create a group of friends inside the Address Book that will be saved inside the user’s pod as a file (here you can find more or less an example in the Address Book section: https://github.com/solid/solid-panes/blob/master/Documentation/conventions.md).
I hope this information is helpful 