i thought of a way... but its probably way off and never going to happen... this is just something i would want to happen because i'm a shiho x shinichi fan... ok so:
He tells Haibara about the situation, then he also gets a hold of his mom and tells her and also his dad. Now, Yukiko and Yuusaku go back to Japan. Since Haibara Ai isn't real, and the black org is after Miyano Shiho, Shiho will take the antidote, put on a disguise of Yukiko, and go to England with Yusaku. Then she will meet up with all of them. The only problem is, both of them will have to stay in England longer, since they would have to wait out the given period of time for the 24 hours to be possible again for their flight back. Of course that means Conan and Ai would be stuck there, most likely with the professor and Yusaku, who will also be helping them on the case.......... anyways, i had to cut out some things since it wouldn't be realistic... like i couldn't have her appear as shiho in front of Ran... it would be too much... and the drug would've worn off long before she sees them... also... i had an idea as to what conan could've done in that situation.
when ran sees him, he says that he and the professor, instead of going on the london eye, they changed their mind and went to see big ben. at one point they accidentally got separated and conan called the professor and told him where he was, so he was waiting for the professor. Yes he did see Shinichi, but that was only momentarily until shinichi ran away.
anyways all i got for now...Detective Kaoko~chan took my other ideas TT.TT hehe, anyways, yeah..
~TacticalWolf~