I'd be very careful. It's a tricky issue. Perhaps say something like
Oh, by the way, I heard you may be getting married soon? If so congratulations!
However be prepared to say nothing about the issue. It is very wise to "plan everything you are going to say", as you have done.
But put this in the optional category in your planning.
"I have heard from a very reliable source ..."
Reliable sources define unreliable sources. :)
But it is totally OK if you ask someone else, to check beforehand.
So, you would ask something like
"Say Mrs Smith. I'm about to meet Steve Jobs for the first time, is it true that he is getting married soon?"
That might be you asking your immediate boss; Steve's secretary; a colleague of Steve's that you know; or another relevant party.
(You do not have to explain yourself ("...I wanted to avoid making a faux pas") as it is totally evident why you are asking and normal to prepare yourself in such a way.)
Note that if you "do" say this and it "works", that is a very positive thing. It's great to show that you are confident enough with business small talk, to "pull off" an incidental social comment like this. It is much to your advantage. But you have to judge on the day whether to leave it.