I think it's quite the contrary. It's questionable if Sera really made the connection between Ai and Shiho in the last case. If she had any suspicions, she had them way before this case, maybe since she deleted that video where Haibara appeared mirrored in Agasa's eye/glasses. I say that because it'd be different to spot that ring on the phone where the image is smaller than on a computer.
As for Okiya, I think he figured out years ago(in real time) and we know he made a promise with a certain someone to protect her. So that leaves us Amuro who broke in Kogoro's office to see that video Mitsuhiko sent and zoomed in to the hand with the ring to figure out the connection. And he was the one to notify the BO about Sherry hiding in Gunma.
now we have to see if Bourbon will check on the shrinking body theory, which can lead to Conan, or Shiho appearing in her normal body will help Conan into dismisssing the shrinking body theory by the BO if Bourbon ever mentions Haibara(Sherry having her body shrink)
