MR LAX
Your clients have both said they didn't know Masime.  Your clients have both said in their testimony that they didn't know who Johannes Masime was.  So how can they even begin to put such a proposition to this witness?  They didn't know who the man was.  You understand?  That was their evidence.  They never heard of him before.  So, they're in no position to say anything about him, and you're therefore in no position to put anything about him to them, other than in the most general of ideas.