Picking Orders in OM, without On-Hand Qty

 Hi,

I had a requirement in Order Management to pick order lines, without having On-Hand Quantity on the Inventory ? Is there a way this can be done ? 

This is primarily because the stock balances are maintained in the legacy system but but the orders are channeled through Order Management and also the inventory allocations / Picking / Shipping are done outside of OM. But the objective is to progress the booked order status to picked / shipped without having to deal with On-Hand Quantity

Thanks