Snippet related to NotifyCollectionChangedAction.Move taken from the code that is used to keep two collections in sync.

NotifyCollectionChangedAction-Move.cs

case NotifyCollectionChangedAction.Move:
{
    // Loosely based on  http://stackoverflow.com/a/450250/86845
    int newIndex = e.NewStartingIndex;
    int oldIndex = e.OldStartingIndex;
    int itemsCount = e.OldItems.Count;

    // get a copy of the items that are to be moved
    List<T> items = otherList.Skip(oldIndex).Take(itemsCount).ToList();

    // remove from old indexes
    otherList.RemoveRange(oldIndex, itemsCount);

    // adjust for index shifts caused by removal
    if (newIndex > oldIndex)
    {
        newIndex -= itemsCount;
    }

    // insert at the new index
    otherList.InsertRange(newIndex, items);
}
break;

WARNING:
This code has a bug. see: https://stackoverflow.com/questions/1256793/mvvm-sync-collections/2177659?noredirect=1#comment90651827_2177659