I have an existing plan for a client I'm doing the 3D version for an architect who does not have the capability. I'm fairly new at this. I need to add a basement under part of the home, now, as they've decided to add one. I'm not sure how to do this. I know how to add a floor above, but not below an existing floor and not sure how to do the partial basement. The rest of the house will be on a slab. Thanks!