Modifier precedence within one event phase

Hi All,

We have a requirement where we have to apply a discount based on the existing discount amount on the order line.

However the first discount on the order line only gets applied at the time of booking as we need all order lines before applying the discount. So we have created a custom event phase for Booking and the first discount gets applied on the order line.

Based on this discount amount I have to apply a second discount. How can I achieve this within the same event phase? As both these discounts are required to be applied at the time of booking?