If your CF's family drinks beer, carry around a glass of apple juice.
If your CF's family drinks mixed drinks, carry around a Dr. Pepper.
or, your CF can say she's sick.
or, last possibility I have for your CF, have your CF's spouse challenge her to not drink alcohol for 60 days. Then, when people ask her why she isn't drinking, she can say that she accepted a challenge to not drink for 60 days (but don't tell them who made the challenge, becasue then they would shame your CF's spouse and make him not drink, too, and that is not necessary!). Maybe even make a bet out of it!
PS. Congrats to your CF!
PSS. How does you CF feel about you telling an entire message board about this pregnancy?!