I have always been told that as the SER, you are responsible for all of the structural engineering performed for the project, including the Specialty Engineered work. Just because the Specialty Engineer sealed and signed the shop drawings, doesn't mean you are not responsible for the liability if something fails. I design and detail all framing connections and don't leave it up to the fabricator's detailer. For joists, as long as the joists specified on the drawings are uniformly loaded members specified using the standard SJI specifications, I don't require seals and signatures on the shop drawings because I sized the joists. For joists with special loadings where KSC type joists won't work, I require a seal and signature for the special joist designs.