This feature is often an option that it is too late to change to once it is realized that it is needed. It is unfortunate that the option is locked after grades are entered, as I would rather it allow me to clear those grades so that I can make a needed change (much as changing the formula in a grade plan does, with a warning), and recalculate affected credits.

While changing this feature, it would also be great to be able to select the grade plan grade specifically that the 'passing grade' should be evaluated from, not just the term.