You might not need the obit, but anyone attempting to research the sisters would need it to identify just who they were.
So, I looked for the obit in the Columbian, Vancouver newspaper.It only showed:
Osborn , Terry C., 63, Vancouver, died Sept. 4, 2005. Vancouver Funeral Chapel, 360-693-3633.
He died on 9/4, not 9/3.
If you don't know the names of his sisters, I would suggest calling the funeral chapel, giving them your information, they could search their records and might have them call you.You might have to give your reason for contact, for their safety and security.