void CreateAllChilds() { List <ChildViewModel> all = (from child in _childRepository.GetChilds() select new ChildViewModel(child, _childRepository)).ToList(); foreach (ChildViewModel cvm in all) { cvm.PropertyChanged += this.OnChildViewModelPropertyChanged; } this.AllChilds = new ObservableCollection <ChildViewModel>(all); this.AllChilds.CollectionChanged += this.OnCollectionChanged; }