Sorry, I was obviously a bit grumpy and interpreted your comment wrongly.
As a blind guide, tracking sighted visitors is easier then you might think. Most sighted visitors will tend to be slow movers. If you ever loose track of one of them, and they dont verbalize on their own, you can always ping 'em by calling their name. For added smoothness, give them a small task like "can you figure out what is sitting on the table in front of you?" afterwards, and they will never even know you lost them for a second.
