This is quite an old question but it is a common subject and I am happy to offer my solution to this type of strategy problem.
Using user variables, one for each hand, set each one to zero in round one.
Then check each hand for favorite in the round your strategy operates and set its variable to the lay odds.
Each following round, check each hand, if its variable is not zero and back odds are greater then set the variable to something that will indicate a win, 999 for example.
Also check from round 4 that hand with not zero variable is winner or tie, if the value is 999 then increment a wins variable and clear a lose variable, if not 999 then do the opposite.
This gives you a running counter of numbers of times the strategy would have won or lost.
Setup your lay bet trigger to lay the favorite if the win/lose counter meets your strategy conditions.
Hoping this might be of some help to others. Good Luck.