A planet pink and yellow: Charles Sheffield, Putting Up Roots (New York: Tor, 1997).
A very similar sort of theme: unwanted children get sent to a colony planet to be trained to work for Foodlines, an interplanetary agribusiness. But when they arrive there is only one technician and he seems a little odd. His actions don't make sense and Josh (the pov, and son of an actress) thinks he's faking. The children include Josh's cousin, Dawn. Autistic but a talented draughtswoman (artist is the wrong word--she reproduces exactly what she sees, without interpretation). Dawn is the first to make contact with an apparently intelligent species and it starts to become clear that the technician (Sol Brewster) has sold the planet to Unimine who practise planetary strip mining, but that he has been aided (ironically) by Foodlines who have worked at hiding the presence of the intelligent species.
At the end the children--aided by Winnie Carlson who masquerades as a technician but is actually a government agent--defeat Sol, Unimine and Foodlines, but--and I realise this is hard to believe--it's all rather plausible. The children are bright and work things out, Winnie is there to help, and when she defeats Sol Brewster with a combination of chilli whipped cream and some judo, she demonstrates the power of intelligence, guile and technique over brute strength.
There are some good (and not too mawkish) discussions of genocide, and there is a strong sense that human beings come in many moralities. We have the usual little scene about delaying sex which I'm coming to expect from this line of juveniles (and they are juveniles in the old style, not YAs), but interestingly, these kids aren't particularly competent and none of them turns out to be brilliant at anything. They are just people, and I liked them very much.
One more Sheffield on my shelf to go, and then I'll move onto someone else.