In the new beta version: While downloading transactions in the usual manner I got a dividend distribution from a stock I don't even own. I Figured out eventually that my son owns it in his account. When he was a kid he had a UGMA account which I managed for him. Now he manages it himself, but the account is still VISIBLE to me at my Fidelity web site.
I have never set FM up to download from this account, and it didn't download the entire account, just that one transaction, and then listed it in my report as if not in any account.