What we’ve found so far (IndexController.php):
– public function skucartAction()
– public function importAction()

$qty_product_added_to_cart[$item->getProductId()] = $item->getQty();
which should contain the single product-quantity.

What would be the best way to remove this verification of the actual product-quantity and simply add the product-quantity indicated on the quickshopping cart-page to the magento cart and therefore allow backorders.

There are several quantity-verifications in IndexController.php and we would need your help in addressing the right one.

many thanks