Pre-closing it was discovered that the appraisal came back under-disclosed by $150.00 on the HUD 1-A. How can this be cured? Do I have to actually re-disclose using a HUD 1, lines 204-209, and would that change the timing requirements? Or since it is pre-closing, can I just show the cure in the appropriate section on the HUD 1-A and give it at closing?

The HUD1A is the alternative to the HUD1. If what you need to disclose cannot be done via the HUD1A, then you must resort to using the HUD1.