Autoscroll implementation for TreeDataGrid

[Dave-Krch]

I have managed to scroll TreeDataGrid using this method in MainWindow.axaml.cs:

private void ScrollTreeDataGrid()
{
    var vm = DataContext as MainWindowViewModel;
    if (vm != null && vm.AutoScrollData)
        tdGrid.Scroll.Offset = tdGrid.Scroll.Offset.WithY(tdGrid.Scroll.Extent.Height);
}

I need to call this every time the source for TreeDataGrid is updated, but i did not find any event that i can use.
Items are being added to the Source using this method in ManWindowVIewModel:

public void AddItem(ASN1Type msg)
{
    DecodedMessages.Add(new ReceivedMessageModel(MsgCount, DateTime.Now, v2Xinterface.Config.Port, v2Xinterface.Config.IPAddress, msg));
    MsgCount++;
}

Is there an event form TreeDataGrid that i am mising? Or is there a way i can acces the TreeDataGrid from the ViewModel and set the scroll there?