I think this brother and sister-in-law are selfish people.In my life,
there is a couple in my family who are also like this, but because they
are so selfish, no one wants to get along with them.
It is wrong for the brother and sister-in-law to be mean and selfish,
but they are the true portrayal of many people. I have also met such
people in reality. In front of interests and family, the test of
humanity is often vulnerable.