topnotch_website/app/Filament/Resources/InvoiceResource/Pages/EditInvoice.php

<?php

namespace App\Filament\Resources\InvoiceResource\Pages;

use App\Filament\Resources\InvoiceResource;
use App\Models\Invoice;
use App\Models\Order;
use Filament\Actions;
use Filament\Resources\Pages\EditRecord;
use Illuminate\Database\Eloquent\Model;

class EditInvoice extends EditRecord
{
    protected static string $resource = InvoiceResource::class;

    protected function mutateFormDataBeforeFill(array $data): array
    {
        $invoice = Invoice::findOrFail($data['id']);

        foreach ($invoice->orders as $order) {
            $data['orders'][] = $order->id;
        }

        return $data;
    }

    protected function handleRecordUpdate(Model $record, array $data): Model
    {
        $record->orders()->delete();

        $record->orders()->saveMany(Order::findMany($data['orders']));

        return $record;
    }

    protected function getHeaderActions(): array
    {
        return [
            Actions\DeleteAction::make(),
        ];
    }
}