Did Firestar tell Mistyfoot and Stonefur that Bluestar is their real mother?

Yes, in A Dangerous Path (book) 5 of the first series, where Riverclan is battling with ThudnerClan to claim Sunningrocks. Mistyfoot and Stonfur, not knowing that Bluestar was their real mother, attacked and threatened her. Firestar was forced to tell these two cats the truth in order to save Bluestar.