CAVEAT: It's entirely likely this is my own stupidty and not a bug.
Check out this JSFiddle. It creates a resizeable box, then adds another dynamically, and tries to initialize that, but only the first box is resizeable.
1) What is the correct way to do this?
2) (If I'm doing it semi-correctly), what is wrong here?
I can't do your second suggestion because in the actual application the user needs to have the opportunity to interact with the page before duplicating things.