I would never assume to know more about a child than the parent does. For all we know that 10 year old could be a real nail/beauty enthusiast and may look after them really well, that's the parents place to decide whether they are suitable or not, not mine. I would be very annoyed if I took my child somewhere for something doing and the therapist assumed to know my child better than me. I'm not in the business of telling other people how to live their lives, I would certainly advise the parent about maintenance, potential nail damage etc etc, but if the parent, in possession of all the facts still decided that the treatment was suitable for her child then I would do it. If other techs disagree then thats absolutely fine, how other people run their salons is entirely their business and I respect that, just as I would expect others to respect my decisions on how I run my business.