I'd just like to say that no matter how GOOD a swimmer a person is, it it STILL dangerous to dive ANYWHERE WHERE THERE IS THE SLIGHTEST CHANCE OF HITTING BOTTOM. I don't care if you're the Richard Petty of swimming, accidents happen, misjudgement happens, teh slightest misalignment or miscalculation can put your daughter/son/cousin into traction for life - do you really want to risk that? I don't think so.
Here's another piece of advice, Monkey see monkey do.....if any of her friends see that, and they'll think it's open season for them to do the same - that's how kids are - by the time you tell them to stop, an accident could have happened, it only takes one dive. If a kid were to get injured in your pool, you won't be living there much longer.