Stop-Loss order is getting value from Parent Order even if sized passed in

[Bo Vargas]

I have the following order with a stop-loss attached. The problem is the Buy Limit order will be reverse the position from Short -> Long; But I need the Stop-Loss size should be for the balance.

Example
Current Position -2 (short)
Buy 4 (long)
New Position 2 (long)
StopLoss Order is 4. I'm passing in the size 2. But somehow this is getting overwritten.

Does anyone know how to fix this? I don't want to submit an order to close the existing position and then open a new order.

self.order = self.buy(exectype=bt.Order.Limit,
                                  size=size,
                                  price=p1,
                                  tif='GTD',
                                  goodTillDate=gtd.strftime('%Y%m%d %H:%M:%S GMT'),
                                  account=self.account,
                                  transmit=False)

o2 = self.sell(exectype=bt.Order.Stop,
                           price=sp,
                           valid=valid2,
                           account=self.account,
                           parent=self.order,
                           size=stop_size,  # We want the stop loss to be half our position; meaning don't reverse
                           transmit=True)

            logging.info('{}: Oref {} / Sell Stop at {}'.format(self.datetime.date(), o2.ref, sp))