I have my home plans about 95% finished and then decided to put a bay window in the study. It's a picture window,$' flanked by a 2' window positioned at 45 degrees. My builder said he would like the basement walls to follow this profile rather than cantilever it past the basement walls. I have the lower level all finished off so when I build the new foundation wall I lose all my lower level, basement, design. Is there a way to mimick the upper level bump out with losing all the detail of the lower level.