I'm trying to add a vaulted ceiling 8:12 over the living room and kitchen. The original roof over the bedrooms is 4:12. I'm using Home Designer Architectural 2020. I can't get the 8:12 vault ceiling, it continually defaults to add the 4:12 ceiling in the living room. I have tried invisible walls, and invisible railings. Can someone help me on this? Floor plan attached.