i have one question,
on our website ,
we sale surgical insturments,
we gave offer to client buy one get one instruments free,after 2-3 month for 7 days..
on those day, received order disturb our inventory, mean if client order a scissor, which we have in stock 50 pieces, after order received its remove 1 item from inventory automatically and left in 49 pieces in stock. but we send 2 pieces to client because we gave offer to [login to view URL] want to add any system when buy one get one offer is on , all items in those order remove in double quantity. you can create a button, when its turn on its automatically decrease item double quantity of order from woocommerce inventory. and when turn off its work normally.