sell product under existing in store

-- Joomla version -- : 3.7.2
-- PHP version -- : 5.6

Hello Guys, i wanna sale in nagative
and dont know how

little describe : i creat a product that i have 5 for sell wanna when my client come to buy it when set 6 of that product the hikashop creat a invoice for he/she. and in report see that we need1 product or i group of users can buy in this way
Thanks for your time and help

Hi,

What you could do is set for example a stock of 105 when you have a stock of 5 and then configure the out of stock notification plugin of HikaShop to notify you when the stock of the products get below 100.
That way, your customers will be able to purchase when the product is out of stock but you'll get notified when there it no more stock so that you can resupply.