Cancel all that's when losing

Hi
Sorry I forgot to describe the trigger and explain what I'm hoping to achieve.
Pleased design a trigger to lay the 1st favourite at SP just before the start at a maximum price of 6.  When the race has started lay off 80% of the potential liability of the 1st favourite @ 1.2 on  All Except the Favourite.  As soon as it looks probable that the 1st favourite is going to lose cancel all of the unmatched All Except the Favourite bets.
The determining the probability of whether the favourite is going to win or lose will depend on various methods including weight of money, its currents price, the stage of the race, differences between first and second and third favourite prices and current position of the SP favourite.  Presumably, the simplest way might be to suggest when the SP price has doubled or reaches 1000.
Using all or parts of these methods devise a robust mechanisms that will make a decision whether to cancel the unmatched bets as soon as possible and before the odds in the race reach 1.2.
Thank you very much,
Tony

hi
i have been working on the trigger.
but too many conditions result in the price reaching 1.20 and less, so i settled for when the back price reaches 1.25 or less then cancel all.
the problem with combining conditions is when a horse shoots from behind to the front the WOM does not activate because it all happens to quick, but the back price always falls quick, even the lay price takes too long to come down close to the back price.
you cannot use the double SP, because again too many times the back price rises quick to 100 and a split second back down to the original price.

mcbee