I think parents get concerned very easily. Doctors tend to become concerned only if there's a reason to do so. For two doctors to be very concerned suggests there was something to be concerned about. What it was I don't know and neither do you.
You accuse the PJ of 'choosing' not to test the twins on 4th May. For them to make a choice the subject had to be discussed. There's no evidence that it was. If the matter wasn't discussed then there was no choice made.
It was not up to the parents to suggest strategy to the PJ. The PJ no doubt had protocols & procedures in place for missing & abducted children. Had senior officers attended the scene when it quickly became apparent something was amiss & noted that 2 other young children, still in situ, were seemingly unresponsive to the stimulus around, them, perhaps more appropriate action could have been taken. Being dependent on a victim asking for a certain procedure to be undertaken is not the way police operate - in fact, it arouses suspicion. But then, every action taken or word spoken by the parents is suspicious in certain quarters.
There were concerns & allegations regarding the amount of alcohol the parents had consumed. I'm surprised no-one is questioning why they weren't subjected to a breath test.