Just put "None, None" for the whole house model on the second row and then you should be able to control individual subset models. Like I have my upper roofline divided into 3 sections called "UpperRoofLeft" "UpperRoofMid" "UpperRoofRight" and then I created a model group with all 3 and then used it to create a whole house model called "UpperRoofline". Then I can have all 4 models on the grid and control individual roof sections independently or as a group. Just make sure they say "None, None" when you want to control them using a different model they belong to. So whole house models don't need to be the whole house either. I use several different groups of whole house models.