Home Appraisal Error

[Amber Hardy]

Hello, I'd love to have some advice if anyone can help. My family member purchased their home less than a year ago, and the home was appraised at the time of the purchase. There were a couple thousand sq ft that should have been included on the appraisal, but they were not. The tax assessor noticed the mistake when they came by. The appraiser has already admitted fault, but the home value was never corrected. How can I help advise my family member in which direction to help get their home value corrected on the previous appraisal? Since the appraiser admitted fault, I feel it should be corrected by that appraiser rather than having to pay for an entirely new appraiser.

Currently they are paying the additional taxes as well as PMI. If the home is worth more, then they shouldn't be paying PMI as well. Is there any way to hold the appraiser accountable for this since they have currently been paying increased taxes and PMI?

Thank you so much in advance for any advice.