Q. My mother-in-law is a problem.

She had often cared for my husband's daughter before we married seven years ago, and now my stepdaughter is 9, our sons are 5 and 2 1/2, and we visit my mother-in-law very regularly.

She has undermined my authority with my own children and with my stepdaughter. They don't see me as an authority figure when she's around because she adds to or takes away from whatever I say. Every get-together is a power struggle.

My husband wants me to treat his daughter as my own child and wants her to respect and obey me, but my mother-in-law has a problem with this policy and has confronted my husband about it.

She's condescending, critical, judgmental and verbally abusive to me, trying to control my actions, thoughts and feelings.

She constantly talks to me about my husband's divorce, and about the ex and her relationship with the ex. They never got along when she was married to my husband, but now she tells me about their wonderful relationship. I show no interest, and have even asked her several times not to do this but it continues.

She waits to get me in a situation in which it would be embarrassing for me to react to her attacks. I am pretty straightforward and these head games are driving me crazy. Raising kids is hard enough; a second marriage is hard too and a stepfamily is even harder.

A. Your mother-in-law and the ex can't destroy your family unless you give them permission to do it. They will, however, make your life miserable if you compete with them on their terms.

There is absolutely no value in worrying about the ex-wife. If your husband had found her so attractive, he would have stayed with her. The mother-in-law is something else.

As you've already discovered, she isn't going to change her ways just because you ask her. In fact, she'll probably get worse. Power struggles -- and drama -- are the breath of life to bullies.

There is no reason to play her games, or to spend so much time with her. Children don't get rewarded for being mean and rude; neither should anyone else.

Tell your husband that you need a break to get your self-confidence back and to help the children realize that their mother, and not their grandmother, is in charge.

You don't even have to have a big scene about it -- since that would only feed her ego -- or to talk about it with the children.

While your husband will go to see his mother sometimes -- with or without the children -- you can cut way back on family visits, by making other plans. You and your husband can help out at a church supper on one regular visiting day; take the children to an amusement park or a museum on another; or simply stay home suddenly because the baby doesn't look well.

When your mother-in-law complains about this lack of attention, tell her you think it best, since she doesn't seem to enjoy your company very much. This puts the burden where it belongs: on her.

Some visits will be inevitable, of course, but make them shorter, or ask her to baby-sit the flock -- or at least the two little boys -- while you and your husband run some major errands.

When you are there, don't engage in her little games or even look annoyed, no matter what she says. At first you can expect her to try another tack, then another, then another -- trying to get a rise out of you -- but the less you bite, the less she'll fish.

When she does embarrass you in public, try to make light of her comments, especially when she talks about the ex-wife. A sympathetic "How nice that you get along with her now. It's too bad you weren't friends when they were married." She'll insist that they were, of course, but you'll just say, "Really? I hadn't heard about that." And then you'll tell her that it really isn't your place to talk about his ex-wife and change the subject, or walk away.

The business of authority is your greatest concern, however. You'll be much wiser to drop this contest, since her style is so destructive. The authoritarian parents get about the same response from their children as the permissive parents: rebellion from pre-K's and teenagers and surly obedience in between.

You want your discipline to be authoritative -- that middle-of-the-road approach that accepts the responsibilities of the parent and respects the mind of a child. Easy conversations, in which you ask your children what they think about the world -- rather than telling them what you think -- will give you more authority over your children than a barrage of orders.

And when it's hard to remember your new resolutions, read "When Families Fight" by Jeffrey Rubin and Carol Rubin (Morrow, $17.95) and "Bradshaw on: The Family" (Health Communications Inc., $9.95). The more comfortable you feel about the way you rear your children, the less threatened you'll feel when others tell you what to do.

Questions may be sent to P.O. Box 15310, Washington, D.C. 20003.