Oh! Both beautiful and heart wrenching! You all lost one brother, but they also gained one. I'm sorry you never met your birth mother. Glad you have found your remaining three siblings though.
Your brother must be saddened by his mother's response.
There's so much in this!
That would describe how me and my brother feel about our current birth family situations.
He's planning a later contact with his half siblings. Once his mother or her husband die. It's kind of a crappy plan, but it's really his only option...
How will he know if one of them dies? And he could still seek out his birth father couldn't he?
He knows exactly who they are and where they are.
The father is harder to track. I have a listed 2nd cousin at 23 and me that is not related to the rest of my family. It's just got to be my uncles kid. I'm awaiting contact as we speak.