Control which gizmo handles the command when more than one are in earshot. I'd like to say "Hey champ, …" to get my phone to do something and "hey blew, …" to g

Control which gizmo handles the command when more than one are in earshot. I'd like to say "Hey champ, …" to get my phone to do something and "hey blew, …" to get my iPad to do something. I'd also like to be able to control the auto-lock duration by voice; I don't want my iPad falling asleep when I'm not touching it in the kitchen. Oh, and I'd like a way to get better directions information from it. Questions like "what exit do I take to get to [sporting goods store]?" would be nice to handle; occasionally I'll need computer assistance for only a tiny leg of the trip, and I'll want to minimize my reliance on a computer's instruction as little as possible.