DEAR ABBY: I am a 14-year-old girl and I'm very worried. My mother is having a baby this summer. I'm happy for her and my stepfather (this is their first baby together), but I think they are expecting me to take on a lot more responsibility than I had anticipated.

My mother and my aunts make comments like, "Get used to changing diapers now, and you'll be a natural once your new brother is born." Or, "Just think, you have a baby sitter in the house so you won't have to worry about getting one."

Well, I don't want to be a mother to this baby. I just want to be a sister, one who loves and holds, and occasionally changes diapers or feeds the baby.

I don't know how to talk to my mother about this. I am afraid that I will upset her and she'll think I don't want this newcomer in our family. She has included me in a lot of the preparations, like shopping and decorating the baby's room.

My mother works full time and my stepfather works six days a week. I already take care of my younger sister after school and when my parents go out occasionally.

I want to enjoy my teen years, free to make my own plans that won't be overruled when my parents want me to baby-sit. Can you give me any suggestions? -- THE OLDEST SISTER

DEAR OLDEST SISTER: It is not unreasonable for your parents to expect you to watch the baby for short periods when they are absent, but they should not depend upon you for all of the baby's care. You will be in school for a good part of the time while your mother works, so she will need another caretaker for your brother in any event.

Show this letter to your parents. The important thing to remember is "compromise": They should not expect you to be an unpaid baby sitter for your new brother; you should expect to pitch in some of the time. You might discover, after the baby arrives, that you want to spend more time with him. Good luck, and congratulations on the new arrival.

DEAR ABBY: I got the shock of my life last week. I live in a well-lighted, expensive neighborhood, in an electric-gated, fenced home.

I was upstairs in my bedroom when suddenly there was a knock on my bedroom door and in walked my two grown sons.

The youngest had climbed over the gated fence, gone into the gated backyard, put a credit card into the breakfast room door, found my purse and got my keys so that he could turn off the alarm in my car, get the remote control and open the gate, so that they could get in, come up the stairs, knock on my door and walk in. I nearly had a heart attack.

Abby, anyone could have done that, and I might not be sitting here writing to you. Everyone, please: Beware and be careful. -- J.P.C. IN L.A.

DEAR J.P.C.: Since you now feel vulnerable in your home, it's time to contact a security company and have someone there evaluate your premises. For openers, you need to purchase a deadbolt lock for the breakfast room. And for your peace of mind, instruct your two budding second-story men to never again enter your home without calling first.

For everything you need to know about wedding planning, order "How to Have a Lovely Wedding." Send a business-sized, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Wedding Booklet, P.O. Box 447, Mount Morris, Ill. 61054-0447. (Postage is included.)

DEAR ABBY: When you told "Confused Heart," "When in doubt, don't" and, " ... the sooner you set her free, the sooner she can begin healing so she can look for someone who will love her," you jumped to the conclusion that what he was experiencing was not love.

If he has not had examples of loving relationships in his life, as his letter indicates, he may need to work through his feelings with a therapist, alone or as a couple. But I'd hate to see him throw away a three-year relationship because of your advice. I have not known a single person contemplating marriage who hasn't experienced doubt, or wondered if the grass wasn't greener with another person.

My advice to "Confused" would be to find a therapist and work out his feelings about love, commitment and relationships. If his current relationship does not work out, he'll have a much clearer idea of what he is looking for in a mate the next time around. And who knows, his girlfriend may just be the "right" one after all. -- NO LONGER CONFUSED THANKS TO THERAPY

DEAR NO LONGER CONFUSED: I received a bushel of well-reasoned responses to the letter from "Confused Heart in Manhattan," the majority from readers who endorsed my answer. But I agree with you; counseling could be very helpful to that doubt-ridden young man. Read on:

DEAR ABBY: I was in a relationship like "Confused Heart's." I ended up dating a man for 13 years. He was too afraid of losing me to let me go, but all the while he never gave himself fully to me because he was always wondering what else was out there. Finally, I left him.

My advice: If, after three years of dating, you still have a difficult time picturing yourself with your friend for the rest of your life -- if it is not how you imagined things should be -- get out. To stay is simply leading your girlfriend on and giving her false hope. To jump into marriage at this point with all your doubts would surely make you another divorce statistic. You would always continue to wonder, as you have put it, "Is there real love out there?" -- HAPPILY MARRIED IN PENNSYLVANIA

DEAR ABBY: I read with great empathy the letter from "Confused Heart," who loved his girlfriend but wasn't sure she was "the one." He wondered if he was living in a fairy tale world, or if there is a real love out there where there are no doubts.

I am 34 years old. I'm being married for the first time in June. As an adolescent I thought I wanted to get married as soon as possible, and regarded every guy I met as a potential mate. I stayed in some bad relationships because it was better than being alone. Over time, I matured, gained some self-esteem, and my expectations about relationships changed. I had several boyfriends, one of whom I grew to care for deeply. But I chose not to marry him because I, too, was unsure of what love was "supposed" to feel like. I didn't want to make a mistake and end up divorced.

Then I met Dan. I can't explain how I knew. I just "knew" Dan was the one for me. I had no doubts. Abby, of all the guys I dated, no one made me feel the way he does. He brings out the best in me. He's my best friend. He never gives me any reason to doubt his love for me.

I'm not saying that everyone should wait as long as I did to get married, but your advice was right on. If in doubt, DON'T -- and that applies to more than just marriage. When it's right, you'll know it. I hope "Confused Heart" makes the right choice. But as for me, I'm ... GLAD I WAITED

DEAR GLAD: Congratulations on your upcoming wedding. I love happy endings.

Abby shares more of her favorite, easy-to-prepare recipes. To order, send a business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, More Favorite Recipes, P.O. Box 447, Mount Morris, Ill. 61054-0447. (Postage is included.)

DEAR ABBY: I am a police officer who spends many hours in local school programs trying to get children to trust police officers. It breaks my heart and angers me to hear an adult tell a child, "See that officer? If you don't behave, he's going to put you in jail."

The last time I heard a mother say this, she was talking to her 3-year-old son! This child then walked up to me almost in tears and asked, "Are you really going to put me to jail?"

That form of "discipline" is not fair to us or to the child. First of all, it's lying to the child. And someday if the child should get lost he will think, "I can't ask a police officer for help because he will put me in jail -- Mommy and Daddy said he would."

Law enforcement officers are there to help parents and children, but parents using us as threats thwart our efforts to protect these little ones. Please, parents, do not alienate your children from us. -- RICHARD K. TEAR, BALCH SPRINGS, TEXAS

DEAR OFFICER TEAR: I have published a number of such letters in the past, but this important message cannot be repeated too often.

Parents, it is essential that children be taught to respect the law and trust its officers, because not only do they fight crime, they also offer aid in times of crisis.

DEAR ABBY: I have enjoyed your columns for many years but have never written to you before.

For a long time I have been concerned and embarrassed because someone in my family, whom I love very much, is a habitual liar. No matter what we say or do, he can't stop lying. He has told so many outrageous stories about the family that he has been disowned many times, but then given a second, third, fourth chance, ad infinitum. Please advise on what might help. Please don't print my name or town. -- CARING IN SOUTH CAROLINA

DEAR CARING: When people lie compulsively, low self-esteem is often the root of the problem. Your family member may need the help of a psychologist to determine the cause of the problem and eliminate this destructive compulsion. I have been told that antidepressants are somewhat effective, but the cure is psychotherapy.

Show him this column and offer your support if he agrees to seek professional help. Good luck.

DEAR ABBY: My husband and I are the proud parents of five children, ages 8, 5, 3, and twins who are nearly a year old. My dilemma begins when I take my children shopping. Abby, you wouldn't believe some of the comments I get: "You sure have your hands full!" "I wouldn't want to pay your grocery bills." "Better you than me." "Lady, you have too many kids!"

I'm beginning to dislike going shopping, and now become automatically defensive if someone approaches me.

My question is, should I respond to these insensitive people? If so, what do I say? I don't want to be rude, but I can't tell you how fed up I am with strangers minding my business. Yes, occasionally there is a good comment, but the negative greatly outweigh the positive. -- SEETHING IN OAKDALE, CONN.

DEAR SEETHING: It would be the better part of wisdom to just smile and keep walking.

To order "How to Write Letters for All Occasions," send a business-sized, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Letter Booklet, P.O. Box 447, Mount Morris, Ill. 61054-0447. (Postage is included.)