I have a question about how to deal with the following issue: There's a family with two kids. The family property is 2 houses (same value, one is home to the family and the other is empty). The older kid gets married, the dad gives him the empty house, and he says the younger one will get the common house when they die. The younger kid gets married too, but since there are no more empty houses, he has to buy a house from his own earnings. 20 years later the father realizes the worth of the two heritages is not equal and he wants to take action about it (he estimates he will live 20 more years).
What could be a correct solution here? Is there a common practice to handle situations like this? Any suggestion?