My father has dementia and ‘forgave’ my brother’s $200,000 house loan. The nursing-home notary said he was of sound mind. What can we do?

Dear Quentin,

My father lent my brother the funds to purchase a house in 2006. The loan was formal and registered in the county. The interest was 4%, and it was a 30-year loan for $300,000. It was bought as an investment property for my brother. It is in a very rural area. 

My parents made many improvements, replacing…