Get and hide all child symbols

I'd like to target all child symbol instances of my mT symbol and hide them.

Something like this (except this doesn't work):

childsymbols_d1 = sym.getSymbol("holder").getSymbol("d1").getSymbol("mT").getChildSymbols();

for(var i=0; i<childsymbols_d1.length; i++){           childsymbols_d1[i].hide();
};

I don't want to use the timeline because I have a lot of child symbols, and would like to do this operation on several other symbols.