I understand but the reality is no parent would let their child go on their own. It would be emotionally traumatic for a young child to go to hospital quarantine independently so parents are forced to pay thousands of baht because the insurance not see that it is a necessity.
if only you test positive then they will remain in hotel quarantine and you will go to hospital. If a child tests positive, an adult can go with them but I've heard of problems that the adult then has to do quarantine after the child is released, even if the adult is negative. Also, I'm not sure if insurance will pay for the adult if the adult goes with them as they are technically negative. The main issue is there is no consistency. It seems to be different for different places/people so whatever answer you may get will be different if it actually happens.