Is my prayer considered valid if I join the Imam in the prostration of forgetfulness (sujud al-sahw), then complete two rak'ahs, say the taslim, and perform the prostration of forgetfulness?

For someone who joins the Imam during the prostration of forgetfulness (sujud al-sahw) that occurs after the salutation (taslim), there is a difference of opinion regarding the validity of their prayer, based on whether this prostration is considered part of the prayer or not. Those who say it is not part of it, such as the Hanbalis and some Malikis, hold that the follower's prayer is invalid, because they joined the Imam in something outside of the prayer. However, those who say it is part of it, which is another view among the Malikis, consider the follower's prayer valid. The preponderant opinion is that if someone joins the Imam in the post-salutation prostration, their prayer is not valid, and they should repeat it. As for someone who catches the Imam during the prostration of forgetfulness before the salutation, they should not prostrate with him, because they did not witness the Imam's forgetfulness.