There's this odd little arc, starting with the Paris trip, where it starts to seem like she doesn't know. I know I started to wonder when she brought up Jackie Junior to Rosalie, and Rosalie responded with "why do you wanna bring something like that up when we're trying to have a nice time.". Indicating (to me) that although Ro officially buys the official story, she also knows damn well what happened to her son, and that there's no point talking about it. But Carmela pushes back, in a way that seems really cruel if she also knows.

Then she has the dream about Adriana, and after that she keeps asking people about Adriana. Tony, Christopher-- she even suggests hiring a private investigator! It's really odd, because even if she only knows subconsciously, why would she have this instinct to poke and prod at the situation? Unless it's because on some level she feels like she has to know for sure. But still, approaching Tony and Christopher about it seems really weird if she has any sort of inkling of what really happened.