Currently, for FOK orders, the BrokerBuy2 API requires that the plugin returns the final fill status. But this means that the plugin blocks for the result on order placement. This wastes precious time that could be use for placing more orders (such as in a large portfolio) or making new calculations.
I don't see why this blocking behavior is necessary. Why not allow FOK orders to be placed simultaneously without blocking? Either BrokerTrade() or callbacks (or both) should be a fine way to give Zorro an order fill update. Something to answer the question, "was this order filled or killed?"