Want to take a summer class that has a time conflict with another class

How should I go about this? There's a math class I need to take that I registered for but the class I also want to take has a lecture the same time as the needed class's discussion. That's the only conflict.

Should I email both lecturers right now? What should I say and when should I ask for the PTA? Ty

Would the person I'm asking the PTA from need proof it's ok w the other prof?