DEAR ABBY: Our son-in-law -- I'll call him Mack -- has become very antagonistic toward my husband and me recently. At first it was subtle, but it is getting worse. Mack and our daughter, "Gina," live about five hours away, so we do not see them often. It is very puzzling.

We have always adored Mack, but now it seems he does everything he can think of to annoy us. For instance, he now refuses to attend church with us when he and Gina visit our home. Numerous other little things also irritate me, and I'm becoming increasingly unhappy with him.

Frankly, Abby, it has reached the point where I no longer want to be around him or have him in my home.

Should I do anything about this, or let it alone? -- J.A. IN W.VA.

DEAR J.A.: It's important for in-laws to have at least a civil relationship with their children's spouses, so please try to get to the bottom of this change in your son-in-law's behavior.

Communication is usually the key to successful resolution of family problems. Call Mack and ask him to level with you about why he's treating you differently. What he says may hurt, but it can also give you a basis on which to begin mending the rift -- if there is one. If you can work this out, you will all be winners, especially if Mack and Gina have children in the future.

DEAR ABBY: Recently, you printed the job description for a best man. Will you please print a job description for the maid/matron of honor, or suggest a book that would explain her duties? -- MATRON OF HONOR

DEAR MATRON: My booklet titled "How to Have a Lovely Wedding" explains not only the duties of the best man, but also those of the other members of the wedding party, as well as countless details that need to be attended to in order to have a memorable wedding. However, since you asked, following are the duties of the maid/matron of honor:

"Usually the sister of the bride is chosen; or if she has no sister, then her closest friend.

"The groom's sister need not be maid or matron of honor unless she is the bride's close friend.

"She generally entertains for the bride before the wedding.

"She attends rehearsal, assists the bride in dressing for the ceremony, provides the 'something borrowed and something blue,' looks after the guests and clergyperson, and stands in the receiving line at the reception.

"During the ceremony, she will hold the bridegroom's ring (if it is a double-ring ceremony) and hand it to the bride at the proper time.

"She will also assist in arranging the bride's veil after the ceremony.

"Don't forget, she is essential as a witness."

DEAR ABBY: I just had to respond to "Mr. Forgettable." I, too, have one of those forgettable faces.

I can be standing three feet from people I have known for years, and they don't recognize me. So I have made it work for me. I am a private investigator in the Deep South. And when people find out that I am a P.I., they are so interested in what I do, they don't forget me anymore. -- HOPES TO STAY FORGETTABLE, GULFPORT, MISS.

DEAR HOPES: You are clever to have turned what some might consider a handicap into an asset. I'll wager you are very adept at your profession.

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: After nearly 40 years of marriage, my parents are in the middle of a divorce. My mother is devastated and humiliated. My father is now living with "Carol," who was my mother's best friend. They are living in what used to be my grandparents' home, less than a mile from Mother.

Mother is trying to get on with her life, but how can she when Carol insists on shopping at the store where my mother works? My father acts like he's done nothing wrong.

Abby, have they lost their minds? I'd like to think my father is sane, but I'm not too sure anymore. I'd greatly appreciate some advice about how to deal with this. -- IRATE IN TEXAS

DEAR IRATE: I hope your mother has a good divorce lawyer, because after having invested 40 years in her marriage she deserves to be left with more than "devastation and humiliation."

In some ways, a divorce is like a death in the family. Your mother is going to need time to grieve and heal. Do not allow her to isolate herself. Keep her busy and help her find new activities to occupy her time and her mind. Exercise is not only good for the body, it can help to keep depression at bay. Encourage her to join a gym or enroll in exercise classes. The more social contacts your mother can make, the better. It's important that she meet new people. Assure her that this is only the end of a chapter, it's not the whole story. And please tell her she is in my prayers.

DEAR ABBY: I am writing in reference to some old coins that were left to me. I have no idea how to determine their worth, if any.

I have some pennies that are dated back to 1842, 1832 and 1803. I'd really like to find out more about them, but I don't know where to begin.

I was hoping that you or one of your experts could advise me where to get an honest appraisal of these coins.

I would appreciate any help you can give me. I am a longtime fan of your column. -- J.McW. IN RIVERSIDE, N.J.

DEAR J.: To get an honest appraisal, consult several coin dealers in your area and compare their estimates. In addition, your public library will have many books on coins and other valuable collectibles, and there are also many magazines for collectors. These should also provide some guidance on the value of your coins. You might consider locating a coin collector's club in your area to learn more about your pennies.

DEAR ABBY: I want to thank you for a letter I wrote you. No, I didn't mail it, but writing the letter and sharing it with my family afterward helped me greatly. It forced me to organize my thoughts and get in touch with my feelings, and it opened up helpful, healing dialogue.

May I suggest to your readers that they try this approach to whatever might be causing their sleepless nights? SENDING the letter is optional, but WRITING it can be essential in coming to terms with, and even solving, life's problems. -- PAM HANSSEN, SAN MATEO, CALIF.

DEAR PAM: I am a firm believer in the healing power of the pen, and I'm certain that many more letters have been written to me than have crossed my desk. For years readers have closed their letters with the statement, "Thank you, Abby ... I feel better just having gotten this off my chest." I'm delighted to help in any way I can, even as a silent sounding board.

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: My son, "Steve," is 18 and will be going to junior college this fall. He will commute back and forth to school and has a part-time job that pays very little.

Steve is basically a good kid. He's not into drugs or alcohol, but he is stubborn and bullheaded. Whenever he needs gas money, clothes ironed or lunches made, I'm usually there to help out. However, when the shoe is on the other foot and I need help with chores and things around the house, he always manages to wiggle out of it, dump the task on his younger brother, or be "too busy" with his friends to stop and help me.

When I try to talk to Steve about it, he gets an attitude and ignores me, or walks away from me, then runs off to be with his friends. If my husband or I try to discuss this with him, he says now that he's 18, he's a man.

Abby, I am thoroughly disgusted with Steve's attitude. What should I do to get him to help around the house? -- TIRED MOM IN MANITO, ILL.

DEAR TIRED MOM: You've done more than enough for this new "man" in the family. I suggest that you make yourself unavailable when Steve needs gas money, clothes ironed or lunches made. Should he ask why, tell him in no uncertain terms that adults are supposed to live cooperatively with each other, and unless he's prepared to cooperate with you and his father, he can assume complete responsibility for his own needs.

DEAR ABBY: This has bothered me for the past 12 years.

I have been married almost 43 years. After our last child moved out, my husband had a midlife crisis. To be specific, he had an affair with someone half his age. Abby, she was younger than two of our children. Out of this affair came a baby. We had DNA testing to be sure it was his.

My question: What is this child to me? What should she call me? She calls me by my first name, which irritates me. Please do not print my name or location. -- IRRITATED

DEAR IRRITATED: The child is not related to you, and if there's a formal designation for someone in your situation, I'm not aware of it. Assuming there are warm feelings between the two of you, select a nickname for her to call you and ask her to please use it.

DEAR ABBY: "Steamed in Boston" complained about food servers asking if he wanted his change back. In my opinion, asking customers if they want their change in order to save a trip back to the table is unprofessional.

My first job as a food server was in a restaurant where the owner forbade us to ask that question. A fellow server told me to say instead, "I'll be right back with your change." That way, the customer could reply, "OK," or, "Keep the change," with no toes stepped on and nothing left in doubt. -- EX-FOOD SERVER IN NEW JERSEY

DEAR EX: Many servers wrote to offer the same suggestion. One said that 90 percent of the time the customer will reply, "There's no need to return the change; it's for you."

Servers reported that the question is used to determine if a trip back to the table is necessary, because they are often swamped, and not having to return to the table saves them time for another customer. To that, I respond, "There are no shortcuts to quality service."

(Everybody has a problem. What's yours? Get it off your chest by writing to Dear Abby, P.O. Box 69440, Los Angeles, Calif. 90069. For a personal reply, please enclose a stamped, self-addressed envelope.)