As for geomantic omen, our home is in the south, and our neighbors all sit in houses facing south. Our neighbor's house faces south, and a mirror is hung on the back wall of our north house.

This is a misunderstanding of Feng Shui. Because that family has a paraplegia, they may ask someone to see him, thinking that paraplegia is caused by heart disease and vascular disease. The five cardiovascular behaviors are fire, and the direction is south. And the south direction of his house is the back wall of your house, so hang a mirror to resolve it. This practice is wrong and useless. Not only will it not have any bad influence on your Feng Shui, but it will also make your back wall thicker, and you will benefit a lot from it. Just have fun!