Ok I have a stack panel and I add child at runtime like so
UserC.ShowData sD = new UserC.ShowData();
ShowDataStackPanel.Children.Add(sD);
I know I can define the margin if I add the item before the runtime but I,ve looked and it's not very clear how to add a user control with a margin at runtime.
Edit
The stackpanel is defined like so
<StackPanel x:Name="ShowDataStackPanel" HorizontalAlignment="Left" Margin="727,33,0,0" VerticalAlignment="Top" Height="617" Width="247"/>
Use Margin propriety for the sD control :
sD.Margin = new Thickness(12,12,0,0);