Laying On The Favorute Depending On Its Price and The Second Favourite's Odds
Lay on the favourite if it is priced between 2.0 and 4.0, it's been at least 30 sec since the beginning of the race, and the second favourite's odds are no more than 6 ticks away from the favourite. Bet only if there are at least 10 runners in the race.
As you can see from the trigger's conditions, it checks if the favourite's odds fit into the given range, and if the second fav's odds are no more than 6 ticks away. The expression r_ticks(r_1_back_price, 6) gives us the back price of the favourite plus 6 ticks. The last two conditions check the time that has passed since the start of the race, and the number of runners.
With very little efforts you can adjust the trigger, so that it will back instead of laying. In that case just change "lay" to "back", then the price range of the favourite, and change "is equal or less than r_ticks(r_1_back_price, 6)" to "is equal or greater than r_ticks(r_1_back_price, 6)". You can certainly change the number "6" to anything else you think appropriate.