What if reported classes for the spring's schedules/classes clash

I am interested in taking a class that would satisfy my IGETC in the spring and want to list it in the application. That said, the class is usually available at odd times, and it might clash with other important classes that I will be taking in the spring. What would I do in that situation if I already have listed these classes in the application but I am unable to take both?

According to the UC application timeline: http://admission.universityofcalifornia.edu/how-to-apply/dates-deadlines/
The last day to update your “in-progress/fall grades” is Jan. 31. By the 31st, you should already have registered your classes for spring semester. Thus, you would know for sure what classes you are taking and which you aren’t before the deadline to submit said list of classes on your UC application. In other words, the main application is Due Nov. 30. January 31 is the last day to update the “My coursework” section on the website. By this time, you will have your class schedule for spring already. Assuming semester system.

Closer inspection, Jan 31 is the “priority deadline” So I assume the quarter system has a different process perhaps.