I am using Home Designer Pro 2021 (pretty new to the software). I have created ceiling planes over 2nd story room that have a railing overlooking the lower living room. The ceiling plane over the second story room has a different pitch than the one over the lower living room they both meet at the top to keep one ceiling line vault. What I need to complete this design is a small vertical section of wall to fill the gap between to the 2 ceiling planes above the railing(see image below). Any help in steps to creating that wall would be appreciated.
