question

I have a CollectionView with some groups. The groups to be inserted are read from a SqLite database, sorted in chronological order and inserted into the CollectionView. Each group has elements, also in chronological order. I have a button that allows me to insert new elements, always within groups, if it already exists, otherwise it creates a new one. when he has to insert new groups, I would like them to be added starting from the last element already present in the CollectionView, then from the bottom, while now they are added to me at the top

Here is the code for both when I insert elements at the start of the page and when I insert elements afterwards

 foreach (MyElement hd in MydataBase.Reerse())
 {
        MyGroup group = new MyGroup("Name Group", new ObservableCollection<MyElement>());
    
         if (!MyCollection.Contains(group))
         {
               MyCollection.Add(group);
         }
        group.Add(hd);
 }

CollectionView.ItemsSource = MyCollection.Reverse();

But when I add them later:

 MyGroup hgroup = new MyGroup("NameGroup", new ObservableCollection<Myelement>());
    
   hgroup.Add(MyElement)
   MyCollection.Add(hgroup);
 CollectionView.ItemsSource = MyCollection.Reverse();

I use the Reverse() method because otherwise when the page starts it displays the elements in reverse order
.

Obviously he has to insert the elements at the beginning if in the Datetime property they have inside them they have a lower date than the other elements that already exist, but the logic inside the app is already there. The problem arises for elements that are antecedent (in the DateTime property) compared to those already in the collection