Using Nintex Forms 2016 in conjunction with SharePoint Server 2016. I have created some conditional formatting and custom validation. I have 3 Yes/No Check Boxes and 1 Single Line Text Box associated with each. Using Rules, I successfully hid each SLTB until it's associated Y/N Box is checked. Within the Control Settings of the SLTBs I have: Validation, Required = Expression, if(Y/N_Box_Control _Structure). The goal is to make the associated SLTBs required if and only if the Y/N Box = Yes/True. All Y/N Boxes are No (unchecked) by default.