Firstly WTAAQ, I do not envy your position here - a very difficult one. I am unsure even having read through these posts what would be the best thing to do.
I would like to say that as far as facts go - a bottle of say, 14% volume wine is actually 11 units. This would take the average healthy human with a healthy liver 11 hours to pass out of their system. The general guide is 1 hour per unit.
If you are found to have alcohol in your blood whilst driving, the powers that be will not care whether you have just drunk alcohol or if it is still in your system from the night before. The end result is a years ban and a 14 week Drink Impaired Drivers Programme which you HAVE to attend. This is obviously preferrable to killing or maiming someone or yourself.
When you drink alcohol, it goes straight to the liver and is processed there before going into the blood stream (alcohol takes approx 5 minutes to reach the brain). Whilst the liver is dealing with the alcohol, it "puts off" processing food and other drink because alcohol is a poison and needs to be dealt with immediately.
If your friend is drinking heavily, it stands to reason that her food is not being processed and is in a "queue" waiting to be dealt with, meanwhile alcohol is given the priority and that is what is entering her blood stream, therefore going into her breast milk.
Does she appear to be losing weight (or infact gaining it?).
Facts are facts at the end of the day, but thinking about it, it may be a start to put a leaflet(s) through her door in secrecy to maybe give her a jolt.
Take a look at www.drinkaware.co.uk. The number they give is a 24hr helpline is 0800 917 8282. They can put you in touch with your local alcohol advice centre.
Thinking of you and wishing you all the best WTAAQ. Please let us know how you get on. x