I've wondered that too!
I suppose, in those days Canarsie was the car crime capital of Brooklyn and I've heard of the Lucchese having junkyards all over Brooklyn.
Testa and Senter were a notorious pair in Canarsie so I guess somewhere down the line they met Casso (or one of his guys who eventually set up an introduction).
Remember Chris Rosenberg got killed because of a little side venture that Roy Demeo originally knew nothing about.
God knows what activities Joey and Anthony were into that Roy didnt know about!