[Shipsyspeepay]

Here as the hadith on when lying is permitted:
Asmaa’ bint Yazeed, , who said: “The Messenger of Allaah said: “Lying is not permissible except for three reasons: lying to one’s wife to please her (for the purpose of arousing love and compassion and prevent disputes), lying during war and lying when reconciling between disputing people.”[At-Tirmithi-Albaani: Sound]. (http://www.islamweb.net/emainpage/in...cles&id=157647)

But then there’s also this more comprehensive hadith:
The sum and substance of this discussion has been derived from the narration ascribed to Umm Kulthoom who said, “The Messenger of Allaah said: “A liar is not the one who tries to bring about reconciliation between the people and speaks good to avert dispute or to convey good.”[Al-Bukhaari and Muslim]. (http://www.islamweb.net/emainpage/in...cles&id=157647)

I think this one explains Hassan RA and Hussain’s RA ‘acting’. Wallahu a’alam.
Barak Allah ta’aala