Hi
The attached trigger file will:
Lay the second favourite at one minute before the off
As soon as the lay bet is matched, it will place a greening-up back bet which will be kept in-play
You can set the profit percentage for the trade in the constant.
You did not specify the selection(s) you wish to trade, so I have set it to second favourite. You can change this in the trigger file.
Please use test mode to try it out.