Multiple Columns for First Level Dependent Dropdown List - google-apps-script

Question

I have a spreadsheet with 4 columns that i am concerned with:
Group (Ferrous/Non-ferrous/etc.)
RI No. (Unique identifier)
Item Description (Name of the chosen RI No. item)
Supplier (Sellers of chosen RI No.)
The flow of data happens like this:
I select Group (say, Ferrous) --> In RI No. column, an automatic dropdown is created, showing RI Nos. of all items under Ferrous category show up --> I select a particular RI No. from this drop-down --> Item Description appears through VLOOKUP --> A drop-down of all sellers selling that item show up in in Supplier column.
Now, I wrote a code which does this work perfectly, but i was wondering if there was a way to make it so that:
I select Group (say, Ferrous) --> In RI No. column AND in Item Description column, an automatic dropdown is created, showing RI Nos. of all items under Ferrous category show up --> If I select RI No., item description gets populated/If I select Item Description, RI No. gets populated --> corresponding suppliers list show up as they do now.
Sample spreadsheet: https://docs.google.com/spreadsheets/d/16qv-OgCIezEuaOm8fQdq91FiQbBny4MzGRIho9ZCY-E/edit#gid=1605627126
The code:
var ws = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
var wsopt = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("sorted items");
var opts = wsopt.getRange(2,1,wsopt.getLastRow()-1,13).getValues();
var firstlevelcolumn = 2;
var secondlevelcolumn = 5;
var thirdlevelcolumn= 6;
var wsopt2 = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("supplier details");
var opts2 = wsopt2.getRange(3,1,wsopt2.getLastRow()-1,12).getValues();
function onEdit(e)
{ var activecell= e.range;
var val = activecell.getValue();
var r= activecell.getRow();
var c= activecell.getColumn();
var wsName= activecell.getSheet().getName();
if (wsName == "JPS")
{
if (wsName == "JPS" && c == firstlevelcolumn && r > 2)
{ applyFirstLevelValidation(val,r);}
if (wsName == "JPS" && c == secondlevelcolumn && r > 2)
{ applySecondLevelValidation(val,r);}
}//JPS
else if (wsName == "DDNI")
{
if (wsName == "DDNI" && c == firstlevelcolumn && r > 2)
{applyFirstLevelValidation(val,r);}
if (wsName == "DDNI" && c == secondlevelcolumn && r > 2)
{ applySecondLevelValidation(val,r);}
}//DDNI
}//close onEdiT
function 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,secondlevelcolumn).clearDataValidations();
ws.getRange(r,thirdlevelcolumn).clearContent();
ws.getRange(r,thirdlevelcolumn).clearDataValidations();
var filteredopts = opts.filter(function(o){return o[0]===val});
var listToApply = filteredopts.map(function(o){return o[1]});
var cell=ws.getRange(r,secondlevelcolumn);
applyValidationToCell(listToApply,cell);
}//close else
}//close applyFirstLevelValidation
function applySecondLevelValidation(val,r)
{
if(val=== "")
{
ws.getRange(r,thirdlevelcolumn).clearContent();
ws.getRange(r,thirdlevelcolumn).clearDataValidations();
} else
{
ws.getRange(r,thirdlevelcolumn).clearContent();
ws.getRange(r,thirdlevelcolumn).clearDataValidations();
var firstlevelcolvalue = ws.getRange(r,firstlevelcolumn).getValue();
var filteredopts2 = opts2.filter(function(o){return o[6]===firstlevelcolvalue && o[4]===val});
var listToApply2 = filteredopts2.map(function(o){return o[0]});
var cell2=ws.getRange(r,thirdlevelcolumn);
applyValidationToCell(listToApply2,cell2);
}//close else
}
function applyValidationToCell(list,cell)
{
var rule = SpreadsheetApp.newDataValidation().requireValueInList(list).build();
cell.setDataValidation(rule);
}