They want the girls to initiate Keltham panicking and departing Cheliax, if Keltham must panic and depart Cheliax; it gives them more steering power. But they didn't want to do it before Keltham had gotten suspicious because if he never got suspicious, it was obviously best to have him here.
And any reason that a girl would now suggest to Keltham that they flee with him inevitably has to be correlated with Keltham getting noticeably suspicious; they wouldn't happen at the same time for no reason. And then he will obviously think of 'they're in the Conspiracy' as an explanation.
So the first move is -