What is someone who owns a house but has reduced mental capacity supposed to do? The house is worth $500k, someone offers them $300k, the person doesn't have th

What is someone who owns a house but has reduced mental capacity supposed to do? The house is worth $500k, someone offers them $300k, the person doesn't have the mental capacity to shop around... I'm just not sure what the right solution here is. I'm afraid it would be even worse if they weren't allowed to sell.