private void ListView_MemberSportsSelection(object sender, SelectionChangedEventArgs e)
        {
            var item = (sender as ListView).SelectedItem as Sport;

            if (item != null)
            {
                Sports.Add(item);
                MemberSports.Remove(item);
                Clubs.Clear();
                foreach (Sport memberSport in MemberSports)
                {
                    foreach (Club clubMemberSport in memberSport.Clubs)
                    {
                        Clubs.Add(clubMemberSport);
                    }
                }

                var memClubs = new List <Club>();
                foreach (Club c in MemberClubs)
                {
                    memClubs.Add(c);
                }

                foreach (Club c in memClubs)
                {
                    foreach (Club club in item.Clubs)
                    {
                        if (club.Id == c.Id)
                        {
                            MemberClubs.Remove(c);
                        }
                    }
                }
            }
        }
 private void ClearFields()
 {
     Member = new Member();
     MemberClubs.Clear();
     MemberSports.Clear();
     Clubs.Clear();
     Sports.Clear();
     foreach (Sport s in AllSports)
     {
         Sports.Add(s);
     }
 }
        private void ListView_SportInSportsSelection(object sender, SelectionChangedEventArgs e)
        {
            var item = (sender as ListView).SelectedItem as Sport;

            if (item != null)
            {
                Sports.Remove(item);
                MemberSports.Add(item);
                Clubs.Clear();
                foreach (Sport s in MemberSports)
                {
                    foreach (Club c in s.Clubs)
                    {
                        Clubs.Add(c);
                    }
                }

                foreach (Club club in MemberClubs)
                {
                    var filteredClub = Clubs.FirstOrDefault(c => c.Id == club.Id);
                    Clubs.Remove(filteredClub);
                }
            }
        }