I barely remember the episode at all.
Count your blessings. "Legacy" is utter crap.
From my rewatch of the episode on Tor.com:
Data being fooled by Ishara actually makes sense. He’s the most literal-minded person imaginable, and he’s never been conned before, so I have no trouble believing that Ishara would be able to play him. But Riker? Picard? Worf? It’s ridiculous that all of them would go from skeptical to accepting just on the basis of a DNA test, and trust Ishara so completely. It wouldn’t be so bad if the cynicism about the Turkanans wasn’t so blatant in the early part of the episode. Picard, Riker, and Worf all agree to play along with Hayne, but to pursue other options. Those other options are never even mentioned again, as they throw all their distrust out the window because one of them happens to be a blood relative of Yar. It’s too extreme—some degree of that would make sense, but that they do a complete 180 in trusting her just makes the main characters look like dumbasses.
The entire episode hinges on a notion that cuts off the air supply to my disbelief. This mess of a planet, one that’s been unable to figure out a workaround to a proximity detector system that’s well over fifteen years old, somehow has access to a Starfleet database that includes listings of crew members who died two-and-a-half years earlier? They must have someone who can hack Starfleet’s computers—yet they’re still stuck with the proximity detectors? Cah-mon!
And then we have the cherry on top of this absurdity: Picard just lets Ishara beam back down to Turkana IV as if nothing happened. First of all, as Riker rightly points out, there should be consequences for her attempted murder of two Starfleet officers (she fired on both Data and Riker with a phaser set to kill, though she apparently has Greedo’s marksmanship...). Secondly, and much more fundamental, though, is that they took Ishara’s implant out. By sending her back to the surface, they have just irrevocably changed the balance of power in favor of the Coalition, who now has the only operative on Turkana IV who can move freely about the colony. This same crew that has twisted itself into a pretzel to stay within the boundaries of the Prime Directive for much less compelling reasons (viz. “Pen Pals” and “Who Watches the Watchers?”) just blithely lets this happen? This is a clear and obvious Prime Directive violation, and Picard’s willing to do it just because he’s embarrassed at the way Ishara ran rings around their emotions?