If you are playing a matched play game, you are allowed to have an understrength unit in an Auxiliary Support Detachment. Due to constraints within Battlescribe, we are not able to reflect this in the error checking. To properly calculate your PL and Points, add the unit you want to take as an understrength unit and then open the context menu on each model in the unit you do not want to use via right click or tap and hold. Then delete the model from that context menu. This will permanently display an error in your list, but it will calculate your points correctly.