So despite your own link stating "If the foreigner is only sitting in the restaurant but not serving customers, not training or managing staff, not cooking and not buying supplies, then he does NOT need a work permit for this. But if he is involved in any of these activities, officially he does need a work permit."
You still stick to your claim. "Totally correct in that if you are married, there is a not very well known law that states you are allowed to help in a small family run business without a work permit in order to provide for your family."
Do you realise your own source of proof contradicts your claim?