Bhagwan, You can select the winner (or placegetter) in a number of races in the one meeting using Allup betting. I believe the reason why this has not been extended to selecting winners in different meetings is probably:
1. Lack of punter interest in the existing Allup product.
2. Technical problems with working out investment amounts if dividend from first race has not been declared before 2nd race starts (eg. punter bets on BR1 and SR1 - selection in BR1 wins but there is a protest which is not resolved when SR1 is run - do you include the winnings in the pool for SR1 or not?)