Product with different combinations and pricing sharing the same stock

[Fileti-o]

Hello, 

 

This is my first post so bear with me - complete newbie to Prestashop. Really appreciate any help here.

 

I use Prestashop 1.6 and sell a product which has the option to add a pedal system for a small increase in price. The way this has been set up is as an attribute: option 1 with pedals (additional x money), option 2 without pedals (standard price). 

 

The product has then been set up with essentially two combinations: by colour and by option of with pedals or without (with pedals has an affect on price).

 

So i´ve got a list of combinations that looks like this: colour 1 with pedals, colour 1 without pedals, colour 2 with pedals, colour 2 without pedals... etc. The product is essentially the same with or without pedals. We sell the product 99% of the time with pedals and the only reason we offer it without is because it makes the price more marketable. 

 

My problem is this: I now have two different sets of quantities: one for product colour with pedals and one for colour without pedals. What I want is for them to share the same quantity of stock - the product is actually made with pedals but we remove them manually if anyone orders it without. 

 

Anyone have any suggestions?

 

Thanks in advance.