Problem with photographing family because her mother also has brown teeth from betel?

Ortho phosphoric aci: Superphosphozyme by biotics will whiten teeth. Use a qtip with few drops use on teeth and rinse off using water with little baking soda to remove any acid (or just rinse thoroughly).

Bigger problem: If your mother in law chews betel she as bigger problems then just stained teeth. People who chew betel have a much greater chance of developing oral cancer then than those who don't chew. I would urge you to ave her evaluated by a dentist. In the mean time you can use photoshop to whiten her teeth in family photos.

Betel nuts: Please encourage her to stop eating betel nuts & to see dentist. They can be carcinogenic. Eating betel nuts can turn lips,mouth & feces red. An overdose of Betel nuts can lead to nausea, vomiting diarrhea, increased salivation, chest pain, arrhythmia, low blood pressure, difficulty breathing, coma & death.