Thank you for your reply, but I think there was a misunderstanding. The issue is not to have a guaranteed price, either for buy or stop loss; rather, we would like to be sure that both orders are in place, i.e. received together by the broker/FCM.
For example, say I send the two orders from my PC, buy and stop; apparently they are sent together, but what really occurs in most platforms is the following:
1) the buy order is sent to the exchange, and a Fill message for the buy only is received from the platform on your PC;
2) the Fill status for the buy order is acknowledged, and only after that the stop is sent to the exchange from your PC. Note there is a temporal delay between 1 and 2.
If the network connection is lost for some reason between 1 and 2, you will lack the stop order and your position is not protected. Very, very unhealthy situation.
What seems unbelievable is that this simple problem is totally neglected. Is there some counterpart that can solve this problem? We repeat, we do not mean to have a guaranteed price.