Medicals for kids

I am looking into migrating with my Australian wife of 12,5 years and our 4 children. We feel quite comfortable meeting the requirements. I just have a single question to which I haven't been able to find a satisfactory answer on the internet.

Yes, current Australian migration legislation requires that ALL children under 18 years of age of a migration applicant are required to meet health requirements (and character requirements, if the child is 16 years of age or more), IRRESPECTIVE of whether or not those children have been included in the migration application. This means that you may be contacted and asked to organise health (and character) checks for your children, even though they have NOT applied to migrate to Australia. giving permission for the child to migrate. Alternatively, the applicant would need to provide a certified copy of a valid court order showing that they or their spouse has the legal right

This indicates all of our children will all need to have a medical check + correct? It is our plan and desire to obtain Australian pbuttports for the children prior to migrating. This would mean that the children would be able to enter Australia at all times. But the medical exam indicates that if an examination is held, one can also fail the examination. And that would suggest that the application of a main applicant could be denied, whilst nothing would be wrong with this applicant. Can you tell me if it is true that our children will need to undergo the medicals? Or am I wrong? (ps, there is nothing wrong with the kids, there is no reason they should fail the examination. It is an expensive and time-consuming effort though)

Kind regards, Bas