More What's My Line?

It's been a while since we've had a Mystery Guest from What's My Line?, and this is an especially fun one from November, 1966.  Actually, multiple-fun.  The guest is Frank Sinatra -- and then when his segment is over, one of the panelists, Mark Goodson (one of the show's producers), says they're going to do something the show has never before done, and that's have him leave...and Sinatra takes his place on the panel.  But that's not the end of it.  Because later they have a second Mystery Guest...and it's Mia Farrow, who shortly before had married  Sinatra.  (In fact, catch how she signs in...)

For those who like to jump around, rather than watch the whole thing, Sinatra comes in at the 3:50 mark, and Farrow shows up around 14:00

https://www.youtube.com/watch?v=v7TY5AckET4