Hi
One thing i notice people do when trying to represent there kids is by using animals: lion cubs, birds etc. I say the best thing to do is to think of all the things you have done with your kids, maybe there was a special time or even something individually special about each one of your children that you could run with.
I think once you’ve thought these things over and explain what’s on your mind to a really talented artist he should be able to far exceed your expectations.
Cheers
Marcus