Can you set a lay price for each horse IE horse #1 $10 @$54 liability, #2 $2 @ $30 liability, #3 $4 @ $30 Liability #4 $20 @ $120 liability etc for the whole field. To be cancelled say 1 minute before jump if not matched. Those that are matched can be backed at SP. And set the lay prices an hour plus before the off.