I have two boys aged 4 and 4 months. Currently I’m whipping out a boob for the youngest in the night at every first cry so as not to wake the older one, but we plan to put little one in his own room and sleep train shortly. With thin walls I’m sure DS4 will wake and wondered about trying him with ear plugs, but struggling to find out whether this is medically ‘safe’ for growing ears? If so, any recommendations on brands? TIA.