<b>screenings only test for markers, not actual genes</b> - so even if she had a screening it would not be full proof.
I can't say that it would matter much if you knew for sure if the genes came down from your mom's side or your dads - even if you did knew and it was the wrong parent - she and her husband could still be carriers of other CF genes. The baby should still be tested based on symptoms and possible family connection.
I think you should mention it to her - hopefully she will take your advise and not just blow you off.
Best wishes!
I can't say that it would matter much if you knew for sure if the genes came down from your mom's side or your dads - even if you did knew and it was the wrong parent - she and her husband could still be carriers of other CF genes. The baby should still be tested based on symptoms and possible family connection.
I think you should mention it to her - hopefully she will take your advise and not just blow you off.
Best wishes!