Rating system to automation

[Jamiethompson]

Hi wondering if someone can tell me if this is possible ,I have rating system where I rate horse with rated prices ,basically it Dutch bets about 4 horses in a races but if 1 or more horses drop below my rated prices I don’t bet in the race .i can work out how to do thst part automatically ,but the next step is that if 1 runnner drops below a rated price I want to cancel that horse and add a substitute runner so I still have 4 horses in that race ,so at the start of a race I have 4 runners and 1 sub runner ,if one runner drops below my rated price I drop that runner and have 3 runner and 1 sub ,make sense ?