Want to make stop loss

i want to make every trade open < make the stop loss the last

i will explain 

this expert for example make buy trade

and every time the price go down it make another buy order and increase the lot

and if go down again it make another buy and increase the lot

(now) the stop loss same for all trades 

i want to make stop loss changes for every trade open like

if the expert make buy order 

and the price go down and make another buy trade < i want the stop loss for the new on the same enter price for the first one

and the same number 3 stop loss < the same enter price for number 2 

and number 4 stop loss < the same enter price for number 3 

and like this for all