I'm looking to create laddered, or scaffold assignments. Specifically, I want to create a homework set with unlimited attempts, but must get 100% correct. Once that score is achieved I want to use webwork to unlocks a quiz over the same material that is taken once for a grade. The idea is to force practice before allowing students to take the graded event. I'm not seeing any options in the HWSets editor that allows the 'opens' option to be an event instead of a date. I am aware that scaffold.pl can do this internal to an assignment, but I'm looking to do this between assignments. Any ideas?