triggers for "follow the money" system -anyone point me in the right direction?

[martins1115]

High - I would like to trial a follow the money system but dont know how to do the triggers - basically i want to back horses that come in drastically from early morning price i.e.
if early morning price is 26 or more back at 15
                                     21                           13
                                     17                           10
                                     15                             9
can anyone tell me how to do this pls -
many thanks - martin