Our clients'/couples' families and family-dynamics are changing, as this CBC article documents on the decline of cousins, so it's far-less likely that the people sitting in front of you look like the old nuclear family you might have expected fifty years ago.
How have I adapted my ceremonies to not say the wrong thing or a stupid thing? I say less things that could sound like a stupid thing to say.
Saying more - correctly - is a great option too but the less you say about specific family and the more you say about family in a general context, the less likely you are to put your foot in your mouth.
It's why I greet a crowd of wedding guests as "friends and family" or "everyone" instead of "ladies and gentlemen", if only because recent statistics show that a certain cohort of the males in that crowd are not at all gentlemen - but that's another letter for another day.