How do I append to separate excel file

public function UploadExcelData(Request $request)
    {
        Log::info('Uploading file:', ['file' => $request->file('file')]);

        //Disabled for now, this cant detect xlsx file correctly, causing it to always fail uploading

        /*  $request->validate([
              'file' => 'required|mimes:xlsx,xls',
          ]);

          */
        $filePath = 'excel/UnitTracker.xlsx';

        if (!Storage::disk('public')->exists($filePath)) {
            return response()->json(['message' => 'UnitTracker.xlsx file not found.'], 404);
        }

        $path = Storage::disk('public')->path($filePath);
        $existingData = Excel::toArray([], $path);


        $uploadedFile = $request->file('file');
        $uploadedData = Excel::toArray([], $uploadedFile);


        if (empty($uploadedData) || empty($uploadedData[0])) {
            return response()->json(['message' => 'Uploaded Excel file contains no data.'], 400);
        }

        /*
        Appended Column
        0 = Machine Type (A)
        1 = Manufacturer (B)
        2 = Model (C)
        3 = Type (D)
        4 = Serial Number (E)
        27 = Customer Name (AB)
        67 = Working Hour (BP)
        68 = Actual Working Hour (BQ)
        120 = Period From (DQ)
        121 = Period To (DR)
        5 = Customer Machine No (F)
        61 = SMR[H] (BJ)
        94 = Fuel Consumption [L/H] (CQ)
        96 = Idling Hour Ratio[%] (CS)
        72 = E Mode In Actual Working Hour (CA)
        */
        $columnsToAppend = [0, 1, 2, 3, 4, 67, 68, 120, 121, 27, 5, 61, 94, 96, 72];
        $sheets = [];

        foreach ($uploadedData as $sheetIndex => $sheet) {
            foreach ($sheet as $rowIndex => $row) {
                $currentSheetIndex = $rowIndex;
                $newRowData = [];
                foreach ($columnsToAppend as $colIndex) {
                    $value = isset($row[$colIndex]) ? $row[$colIndex] : null;

                    // Convert Working Hour (67) and Actual Working Hour (68) to dates
                    if (preg_match('/^d{2}/d{2}/d{4}$/', $value)) {
                        $newRowData[] = CarbonCarbon::createFromFormat('m/d/Y', $value)->toDateString();

                    } else {
                        $newRowData[] = $value;
                    }
                }

                if (isset($existingData[$currentSheetIndex])) {
                    $sheetData = $existingData[$currentSheetIndex];
                } else {
                    $sheetData = [];
                }

                $sheets[$currentSheetIndex] = new DataExport($sheetData, [$newRowData]);
            }
        }

        $multiSheetExport = new RowHandlerExport($sheets);


        Excel::store(new RowHandlerExport($sheets), $filePath, 'public');

        $originalName = $uploadedFile->getClientOriginalName();
        Log::info('Data appended from file: ' . $originalName);

        return response()->json(['message' => 'Data appended successfully.'], 200);
    }

So I was trying to append the excel data basically like this
File 1 row 1 is appended to sheet 1 row 1.
File 2 row 1 is appended to sheet 1 row 2.
File 1 row 2 is appended to sheet 2 row 1.
File 2 row 2 is appended to sheet 2 row 2.

it works here, but rn it’s only for a single file, I need to be able to append this to a new excel file based on the customer name (row 27) in excel

How do I append it to different excel file, I’m kinda clueless on this