We need to take a membership number and apply a fixed discount. No change if void or not a valid number. The membership number comes from a database table. The database is refreshed weekly.
We need to add a variable local fee depending on the location of the buyer- but the location is customized as a Chapter. Perhaps all customers could be put into a customer group as the basis for adding the fee- if all customers can be forced to choose a Chapter from a drop-down during registration.
Essentially, we need to alter prices based on customized customer registration field data compared to a database table.