Ehtay Mullah, the brother I never knew

When my parents first moved to Bradford, England in the 1970s, my dad adopted a Bangladeshi kid named Ehtay Mullah who was 17 or 18 years old and an orphan. My dad brought him to England in order to give him a better life because he himself was an orphan at a young age (my dad's parents died when he was a boy). As soon as Ehtay Mullah came to Bradford, he took a job somewhere and was gone most of the day. Before long, he was going to college, moving on to bigger and better things, moving up in the world, forgetting the man (my dad) who gave him a better life. In those first few years my parents were in Bradford, we rarely heard from him. The last time my dad spoke about him (and this was when I was a kid), he said that Ethay Mullah had moved to London, got married after getting a high paying job, and started a family. It's sad because I never even knew the man. Anyway, the reason I'm telling you this is this: My sister did something wrong a while back and my brother said to the entire family, "She's not part of this family anymore! She's not my sister! She's Ethay Mullah's sister," meaning she's the kin of somone we no longer know.