I am not at all shocked the Empire didn't see the point in killing a divorced woman's ex-husband. As for the daughter, hasn't it been speculated the family she married into has enough influence to protect her? For that matter, given Perrin is getting cozy with Leida's mother-in-law, it's not that much of a stretch their influence also protected him. So no, by sparing Mon Mothma's family, Palpatine isn't being nicer than the Dominion, just being more politically conscious.Was rewatching some DS9 and I think Gilroy maybe stumbled just a tiny bit at the end by letting Perrin live. Damar's wife and kid were executed by the Dominion immediately after he defected. If Emperor Palpatine of all people comes across as nicer than the Founders of the Dominion, then someone's writing him wrong.