@ pooya87 - your proposed solution will not be provably fair, and is described in the OP's
other thread. In your example, if Alice is a sockpuppet of the casino, it could wait until Bob reveals his seed based if the three combined seeds are a winning hand for the casino.
as i explained in condition 3, the player that refuses to reveal its seed is disqualified and if games on such casino have more occurrence of something like this then the game and the casino will lose its reputation and nobody will play there anymore.
besides what is being explained here could be the case with any game not just this. for example in dice if you roll something that is supposed to win you a big reward the casino can show you an error saying something unknown went wrong instead of revealing their seed and giving you the number and reward. they wouldn't need a third player "sockpuppet" either.