Event on form close

Happy Friday! I know some of us, myself included, have checked mentally and have already started the weekend but I thought I would risk the question.

I need to add a modification to the WMSBillOfLadingCarrier form in order to trigger custom code to recalculate total weight for given a BOL number in order to update WMSBillOfLadingOrder. Should I override the finalize or close methods on the form? In which case I'm uncertain if doing so will bypass some current function. Or should I override the validateWrite method on WMSBillOfLadingCarrier?

I'm wondering what best practices are for this situation, and what other recommendations may there be?

Thanks very much!