Alcoholism is a progressive disease. It's quite likely once she starts this behavior it may become more common. You said she is with a female friend, so it may be the friend was the trigger for all of this.
My children are ages 8 and 14 currently. I just recently divorced my X husband who is an alcoholic. I will say that things got a lot better with my children when I stopped covering up for his bad behavior and educated them on alcoholism and the boundaries they need to keep in place for themselves, and how to protect themselves (a big example, not getting in a car with their father or anyone who has been drinking). I took them to counseling and also we attended Celebrate Recovery. A lot of the Celebrate Recoverys have age appropriate groups for children.
Good luck and God Bless to you for helping her children.