You’re master account has to be an individual for it to stay non professional. An LLC automatically makes it professional account. For FA account I believe you can manage up to 15 accounts and stay non pro.
i think in that case, we need to "Save" the order for watchlist, place order. Cancel partially filled, reload with new price.
I saw in tradehawk, "Save" strategy is nice it shows price at the time of saving, with current price and also shows P/L.