We are a family of six grown children and one of us is an extreme alcoholic, with memory blackouts.

She has two children -- ages 4 and 20 months -- and is drinking heavily, after 18 months of sobriety.

Nobody wants to get involved with her because she is spiteful and vindictive. Four years ago we called Social Services and she's been retaliating ever since.

I'm worried about the children, however, and feel something must be done. I'm sure there are a lot of things that we don't know about, but I do know that the baby fell down a flight of stairs and our sister didn't take her to the doctor.

Her husband is also an alcoholic -- although not as bad as she is -- but he is no help to her. He runs his own business, and has made it his No. 1 priority.

Our sister can't stop drinking on her own without risking a seizure. She has to get professional treatment again, but I'm not getting any family support on this, because no one wants to take her on.

I'm willing to do my part to help -- taking care of the children while she gets treatment -- but I think the others should get involved too. I don't want to alienate myself from my family, but I can't just sit back and watch.

Your sister is suffering from one of the most painful, heartbreaking diseases of all.

Suffering, however, is the key word. If you find it painful to watch her destroy her life, imagine how much it hurts her to destroy it. And that, of course, is what she's doing, for alcoholism is a progressive, terminal illness.

Although your sister is the only one who can break the lock it has on her, she must have help. As hard as she has tried -- and 18 months of sobriety is very, very hard -- her compulsion to drink is now greater than her will to live.

Since you feel morally bound to help her, you're the one to intervene, but don't ask your siblings to join you. We can't expect others to follow our banners; they resent it if we try.

It's a matter of how to help your sister, not if. You can't help her if you ignore the problem, since it won't go away, or if you pick up the pieces, since she'd just drink more, or if you confront her, since that technique didn't work before and, given her nature, it might be disastrous now.

Use discretion instead. Just go about your mission quietly, starting with a confidential visit to a supervisor at Social Services. Spell out your concerns about child neglect, ask the office to intervene -- and take down the names of the people you see and the advice they give. It's always wise to have a record when you deal with the shifting personnel of a bureaucracy.

You should also meet with the officer in charge of your sister's police precinct, and ask him to keep a special watch for your sister and brother-in-law on the road. Many alcoholics are given court-ordered treatment after they break traffic laws.

And both the family doctor and the pediatrician need to know about the situation, and to know that you could take care of the children if they get your sister into treatment.

They may persuade her with the results of a full medical workup on her liver, her metabolism, her nervous system and her nutrition, but seizures and blackouts should be enough. These are both very, very serious signs of alcoholism.

A 30-day in-patient program, beginning in the detox unit, is essential, followed by months of after-care and a lifetime of AA meetings.

Your sister will have many problems to work out as a wife and mother, particularly since her husband is also addicted to alcohol. He won't like to lose his old drinking companion, and he won't like it when she tries to make him stop drinking too.

She'll also need to know that a predisposition to alcoholism is often inherited and that women are more susceptible to the disease than men, even if they're the same weight. Not only does estrogen lessen their ability to process alcohol -- making premenstrual episodes worse -- but new studies show that women can't process alcohol as well as men because they simply don't have as much of a key enzyme in the stomach. This shortage makes them send 30 percent more alcohol into the bloodstream than men do and even more as the disease gets worse, for alcoholism destroys these enzymes in both men and women. The more your sister knows about the disease, the less she will blame herself and the less defensive she will be.

You and your siblings need help too. You'll find guidance at Al-Anon meetings and some solid information from "The Facts About Drinking" by Gail Gleason Milgram (Consumer Reports, $16.95) and "Understanding The Alcoholic's Mind" by Arnold M. Ludwig (Oxford, $16.95).

Added understanding will help you forgive yourselves if you can't change your sister and to accept her children whatever she does. She needs to know that you will care for them now, if she cannot; that you'll be there for her when she does quit; and that you won't sit in judgment. Whether she's going down the mountain or climbing up, she's doing it with a rock on her back. There's no need to add to her freight. Questions may be sent to P.O. Box 15310, Washington, D.C. 20003.

1991, Tribune Media Services Inc.