In your triggers you may use the match_l_book variable - it's the book % for matching selections (selected by the trigger).
For example to dutch on the first 3 favourites:
Action: dutch lay
Selections: All matching selections
Conditions are met:
Any Selection's Rank is equal or less than 3
AND Trigger Expression match_l_book is greater than 105
To watch this value you have to create another trigger:
Action: Set user variable MyBook value match_l_book individually for each market
Execute: once per second
Selections: All matching selections
Conditions: Any Selection's Rank is equal or less than 3
Or to watch the book % of the existent prices:
Action: Set user variable MyBook value match_l_book individually for each market
Execute: once per second
Selections: All matching selections
Conditions: Any Selection's Lay Price is greater than 1
Then enter into the "View variables" list the MyBook variable.