What is the ruling on someone who caught up with the Imam prostrating and added an extra prostration, and what is the ruling on the Imam bearing it on behalf of the worshiper?

If the follower adds an extra prostration due to forgetfulness, the Imam bears this on his behalf, regardless of whether the follower joined late or not. However, if a follower who joined late stands up to make up what he missed after the Imam's salutation, and then commits an act of forgetfulness, the Imam does not bear this forgetfulness on his behalf, because the Imamate connection has been severed. The follower is subservient to the Imam, and his ruling in terms of forgetfulness or lack thereof is the same as the Imam's.