Knowledge itself is power and the most important thing for all of the clones at this point in time is to gain as much of it as they can.
We learned on Orphan Black Season 2 Episode 5 that Rachel's position at Dyad is a step above Dr. Leekie's, but that doesn't mean she can escape the humiliation of a monitor. She is, after all, still a clone and a non-reproducing one at that.
She can call the shots, she thinks, and chooses Paul as her new monitor with Daniel dead and gone thanks to Helena.
Sarah's borderline hysteria at the sight of her sestra has passed and she's trusting Helena to help her find information about their shared past. That becomes even more important when Felix is framed for the murder of a police officer and all hands are needed on deck to free him.