If you want to be mechazek your kids, put the sign on the INSIDE of the door so the whole family sees it, A sign OUTSIDE the door is a broadcast to the whole world, you can uphold higher standards without telling anyone who didnt even ask, and if you only eat THAT Hashghca, you dont need to tell someone who eats from a difference hashcha that most eat from (I am talking about generally accepted hashghcas, not ones most dont hold from) why you dont eat from THAT hashghca
