Centralize stock handling across multiple Virtuemart shops

[Genius WebDesign]

Hi,

My client has multiple Virtuemart shops and they all have the same inventory based on SKU but they are all seperate Joomla installations with their own databases because the product names and prices must be different in each shop.
Now, my client wants to have a centralized stock handling across all shops, meaning that each time an order is shipped in "shop1" the procut stock handling must also apply in "shop2", "shop3" etc..

Basically the idea is that each time an order is shipped the quantity of all the products in that order must be reduced in all shops.

Does anyone know a smart way to achieve this?

I have investigated this a little bit and it seems to be a solution if I could extend this function the right way:
"handleStockAfterStatusChangedPerProduct"  in /administrator/components/com_virtuemart/models/orders.php