Filling Order Positions?

I believe its called "filling order"
If price is retracing upwards, but the overall trend is bullish, trader will have short orders at each level of resistance.
Wouldn't it be better to wait for a confirmation that the trend is continuing down before adding shorts? And if I'm adding these shorts at these different levels , let say 135.00, 137 and the last short is added at 139, what would my all SL be? above where my final short would be?

thanks.

Everybody has his own srategy of trading and it deneds on him when he decides to trade.