Give the girl a break, she as been very silly and will pay a high price in terms of her employment and by being publicly named and shamed, but she's still someone Daughter and a human being. There is next to no chance that what she did would have impared the safety of the flight, however there are rules and she was on the wrong side of line.
Right now there will be people all over the world leaving a bar and thinking "i ought not to have had that last drink" on duty in 6 hours or less, there will be a few less beacuse of the publicity surrounding this case.
There is no mileage for bmi in dumping her, yes she will get sacked, but i suspect she will have resigned already.