Opening Cubase 8.5 sesh that includes Reason(Rewire)

After much procrastination I finally committed to switching from Sonar Platinum to Cubase Pro 8.5, and am mostly thrilled minus one glaring issue, implementing Reason as a synth rack via rewire. With Sonar I could easily save a session with Reason in it and upon opening the session Reason would load automatically along with everything else. Cubase: After struggling with inputs not assigned errors I learned to follow a sequence of open Cubase, open Reason, open session. Do I really need to do this? Am I missing something. If Sonar can open Reason automatically, why can’t Cubase?

Grateful for any insight.