Sorry I haven't updated sooner.
The Mormons came back to visit my son's house as they'd said they would do.
All in all, my son thought they were nice people. However, they were obviously sticking to a script.
My son challenged them on the archaeological anomalies, and they replied "the BOM hasn't changed".
???
My son then countered with the fact that Joseph Smith changed the book after he'd married 4 wives.
I can't even remember what my son said they said, it was that unrelated to the question.
Basically, my son asked good questions, and the Mormons didn't have answers - just words by rote.
My son said they were very nice and they blessed my son and his friends when they left, which my son thought was a "genuine moment, although it meant nothing".