/// <summary> Adds a user to the list of users which belong to this user group </summary>
        /// <param name="User"> Small user object which holds the very basic information about this user </param>
        public void Add_User(User_Group_Member User)
        {
            if (users == null)
            {
                users = new List <User_Group_Member>();
            }

            users.Add(User);
        }
        /// <summary> Adds a user to the list of users which belong to this user group </summary>
        /// <param name="User"> Small user object which holds the very basic information about this user </param>
        public void Add_User(User_Group_Member User)
        {
            if (users == null) users = new List<User_Group_Member>();

            users.Add(User);
        }