Autumn days, grandsons and colds

Darling daughter (DD), son-in-law (SONIL) and dearest grandson (DGS) arrived home from a very rainy holiday in Greece (where they lived until last October) on the coldest day of the autumn so far whereas it had been t-shirt weather until Wednesday. She certainly didn't look a happy bunny when she knocked on the door at 8am for the car keys - at SONIL's request as youngest DGS had her up all night as he has a cold and SONIL believes being out in the cold and wind causes colds - she reckoned there is no arguing with him even though like me she doesn't agree with that view or with using the car for a 5 minute walk each way... kept lips buttoned when he returned the keys as it is not worth getting into the middle of their disputes unless someone's well being is seriously at risk. When would you get involved (if ever)? I usually only get involved when directly asked for advice but always try to not play the blame game and remain neutral, not easy but meditation and mindfulness help. Ommmmmmmmmmmm