In FCS there are some different types of groups. At the beginning on the platform there are ordinary groups, which are being transformed to master groups after you add one or more Subgroup(s) to them.

Funtionality rules:

• You can not add or remove an user from a master group directly. Any attempt to do such a request will not be executed. 
• Adding an user to a subgroup results in adding him/her also to the master group, if he is not already a member of the last one.
• Removing an user from a subgroup yields the following: if the user is not a member of any other subgroups of the same mastergroup, then he is also removed from the master group; otherwise he is only removed from the subgroup.
• Hiding a group does not empty the group. When the group becomes unhidden, the users remain there.