How do I code 3 series dependent drop down on multiple sheets?

I have a code to run a 3 tier dependent drop down list - it currently works for one sheet in my workbook named "BlankNode" but I need it to work for ~20 different sheets. I tried adding a script for each sheet but only the last one I edit will work. I think I need a loop function for a range of sheets but that doesn't seem to be working. Am I able to get the below code to run on multiple sheets?

 var mainWsName = "BlankNode";var optionsWsName = "options"var firstLevelColumn = 2;var secondLevelColumn = 3;var thirdLevelColumn = 4;var ws = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(mainWsName);var wsOptions = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(optionsWsName);var options = wsOptions.getRange(2, 1, wsOptions.getLastRow()-1,3).getValues();function onEdit(activeCell){  var activeCell = ws.getActiveCell();  var val = activeCell.getValue();  var r = activeCell.getRow()  var c = activeCell.getColumn()  var wsName = activeCell.getSheet().getName();  if(wsName === mainWsName && c === firstLevelColumn && r > 1){    applyFirstLevelValidation(val,r);  }else if(wsName === mainWsName && c === secondLevelColumn && r > 1){    applySecondLevelValidation(val,r);  }  }// end onEditfunction applyFirstLevelValidation(val,r){    if(val == ""){      ws.getRange(r,secondLevelColumn).clearContent();      ws.getRange(r,secondLevelColumn).clearDataValidations();      ws.getRange(r,thirdLevelColumn).clearContent();      ws.getRange(r,thirdLevelColumn).clearDataValidations();    } else {      ws.getRange(r,secondLevelColumn).clearContent();      ws.getRange(r,thirdLevelColumn).clearContent();      ws.getRange(r,secondLevelColumn).clearDataValidations();      ws.getRange(r,thirdLevelColumn).clearDataValidations();      var filteredOptions = options.filter(function(o){ return o[0] === val });      var listToApply = filteredOptions.map(function(o){ return o[1] });      var cell = ws.getRange(r,secondLevelColumn);      applyValidationToCell(listToApply,cell);    }}function applySecondLevelValidation(val,r){    if(val == ""){      ws.getRange(r,thirdLevelColumn).clearContent();      ws.getRange(r,thirdLevelColumn).clearDataValidations();    } else {      ws.getRange(r,thirdLevelColumn).clearContent();      var firstLevelColValue = ws.getRange(r, firstLevelColumn).getValue();      var filteredOptions = options.filter(function(o){ return o[0] === firstLevelColValue && o[1] === val });      var listToApply = filteredOptions.map(function(o){ return o[2] });      var cell = ws.getRange(r,thirdLevelColumn);      applyValidationToCell(listToApply,cell);    }}function applyValidationToCell(list,cell){  var rule = SpreadsheetApp  .newDataValidation()  .requireValueInList(list)    .setAllowInvalid(false)  .build();  cell.setDataValidation(rule);}