I haven't seen a list. This is still one of those gray areas, because the brochure doesn't speak to it at all, but it is done in practice just about everywhere. Even the F&W booths did it last year, and that was a surprise to just about everyone. If you know ahead of time where you want to do it, just go ask. You'll get a better answer there than you will here. Even if someone says they did it yesterday, you may get a different CM who has no idea what you're talking about or the one who did do it got a CM that just did it. It never hurts to ask.