I am using Uk standards Library for designing Stormwater drains. How do I add a new Feature definition/ Cell Library which is not in the Cell Library for a new Chamber (image attached for reference) in ORD. I tried using the Add New Template option and add/Copy the existing Chamber/ Manhole in Explorer Tab- the UK Standards Library. I want to add a new chamber wherein I can edit the size of the new Chamber (one shown in images below) added.