Let me try to explain what I'm doing here:
* calling options.fn(frame) in nested {{#using}} blocks is only giving me the reified lists in the context stack, not any of the original objects that should be in the context stack (this is a bug, but c'est la vie).  This doesn't work where I need to set up the meeting's people and compare against the response's people.
* I want to preserve the context stack's "___st4ck3d" property while concatting a new item to the end of it (which actually creates a new array).  Using a combination of concat and $.extend gives me that.  Recall that without having ___st4ck3d set, the context stack gets treated as a simple array and breaks everything.
* What's actually happening with default_audit_title is that the instance is the current context.  Because of the way can.view sets up the stack, the current context gets pushed on the top of the stack if options.fn/options.inverse is called with a stack.  This means that what's happening is that you're getting the program object from instance (which is the current context when {{#using}} is called) instead of the program property of the defer_render frame.
* Other things may be broken, but in all cases are easy to work around if they're broken.  Just change the name of the hash key in #using and use that changed key.
* We should upgrade to CanJS 1.8 or later (2.0.1?) and fix our 50+ mustache helpers to work with the Scope object ASAP.