How to request a mandatory parent item of some work item types?

as far as I can tell, there is no built in advisor/precondition you can use. You would have to create a custom work item save advisor and deploy that on your server. This would be a Java Server Extension. https://rsjazz.wordpress.com/2015/09/30/learning-to-fly-getting-started-with-the-rtc-java-apis/ explains the APIS available for EWM and points to the EWM/RTC Extensions Workshop that you would follow to setup an development environment. That workshop shows a participant/follow up action, but developing an advisor/pre-condition is really pretty much the same. https://rsjazz.wordpress.com/?s=advisor&submit=Search shows several advisor examples. Detecting a parent work item is shown in https://rsjazz.wordpress.com/2012/11/27/resolve-parent-if-all-children-are-resolved-participant/ and in https://rsjazz.wordpress.com/2012/07/31/rtc-update-parent-duration-estimation-and-effort-participant/ .