Trouble with the mail

This bit of mail was returned to me. If you look closely, there is a small chunk of the original envelope inside a larger envelope. (I whited out the address.)

At the top is "Return for better address." Does that mean that if I put a complete address and new stamp on it this would go through the mail?

What now?

I found an old notebook. I used to keep it in my purse to write down shopping lists, book recommendations, ideas, etc. There was only one page with writing on it. Here's what it said:

Father and mother separated to different sons' houses -- then they find their long lost adopted son at a car dealership by the train station.

Huh?