I created some users husband, wife, kid1, kid2 and some groups: parents, family, kids.
Now I created shared folders: e.g. husband, wife are members of parents, all users are part of family
Name: Parents
groups: Parents@mydomain.tld
ACL: No special set
Name: Family
groups: family@mydomain.tld
ACL: No special set
Now these shared folders are show within SoGo. for all users. This means “parents” is shown for kid1 and kid2, respectively. Ok, the do not have access to the mail.