What this article explains is consistent with my experience with PTO, which essentially works the same way as Lacerte.  I tried preparing a CA return with Sch S but didn't get any diagnostic for manually attaching the other state's return.  That means PTO (and most likely Lacerte) will automatically transmit a copy of the other state's return to FTB.

Unfortunately, I can't locate a Lacrete version of the article (which often parallel those of PTO).  Hopefully, @IntuitBettyJo will come back with a definite answer for Lacerte soon.

https://proconnect.intuit.com/community/help-articles/help/e-filing-state-tax-returns-when-attachmen...