TOPIC: Late fees for custom fields

Here is what I'm trying to accomplish:

Event has no base fee, but 4 optional seminars during the event that each carry separate fees. I'm going to use the custom fields functionality to add the seminars and their individual cost to the registration form and was wondering if there was a way to add a late fee to each custom field individually?

Any suggestions are appreciated. Thank you.

The built in late fee system will apply the fee to the cost of registration, even if the base fee is $0. However, you can not add separate fees to each custom field.