I guess you don't have to cover pre-existing conditions if you decide to eliminate an entire class of insured.
Actually that is not true. If they cover the child as a dependent they have to include px conditions.
I have a $0 commission case on the books with Cigna, courtesy of my website. Someone found me, applied direct to Cigna without my assistance. Wife was rejected, husband accepted as was one of the kids who apparently was uninsurable.
I say apparently because the app was clean (all "no" answers) yet somehow Cigna discovered enough info to decline an adult, rate the other and rate the uninsurable child to the max.
Fortunately, I did not do anything to earn my $0 commission.