allow order only with specific quanties

Hi,

Thanks to views, you can modify the "quantity" view in order to display a dropdown list instead of the classical input text field.
After that, if you want more "security", you can add some checks in the "checkout step" view to check products' quantities.

Regards,

You might also be able to do it more simply:
One simple way is to enter the price for 6 bottles and consider the product as a pack of six bottles.
Another way is to create a characteristic for the number of bottles and in each variant of the product enter the corresponding price.

If you want to have the stock handled on a per bottle basis, you won't be able to use a characteristic for the selection.
In that case you should create a quantity display override and not use characteristics:
www.hikashop.com/en/forum/4-how-to/15254...uantity-ordered.html

The simplest is to change the line:
<input id="hikashop_checkout_quantity_<?php echo $row->cart_product_id;?>" type="text" name="item[<?php echo $row->cart_product_id;?>]" class="hikashop_product_quantity_field" value="<?php echo $row->cart_product_quantity; ?>" onchange="var qty_field = document.getElementById('hikashop_checkout_quantity_<?php echo $row->cart_product_id;?>'); if (qty_field){<?php echo $input; ?>}" />

to:
<?php echo $row->cart_product_quantity; ?>

so that the user cannot change the quantities on the checkout.

You can also transform that line to a select.