DEAR ABBY: My husband, "John," and I are in our mid-20s. We have been married for over a year. During this time his younger sister, "Caitlin," has made numerous trips to visit us. She is charming, thoughtful and wholesome, and I look forward to her visits. Not only are Caitlin and John very close, but I consider her to be my best friend. Although I enjoy her company, there is one thing about her visits I'm not crazy about.

John and I live in a one-bedroom apartment, and she has only the den couch to sleep on. While this provides her no privacy, she still prefers sleeping in the buff. When she undresses for bed, it makes no difference if John is present or not. When she wakes up in the morning, she'll stroll into the kitchen "as is" for coffee while on her way to take a shower. If John and I are in the kitchen, too, she's not shy about standing around in her birthday suit, chit-chatting with us as she sips her coffee. I've always maintained a casual attitude about this, but actually, I would prefer not to see her walking around in the nude.

I realize that females are not required to cover themselves around males in their own family. I wasn't that modest around my brother, either. But now that I'm married to Caitlin's brother, is it still acceptable? I'm very uncomfortable. -- SENSITIVE SISTER-IN-LAW

DEAR "SIS": If you and your sister-in-law are so close that you consider her your best friend, level with her about the fact that her nudity is making you uncomfortable. On her next visit, have a nice terry-cloth bathrobe waiting for her in the den. If she forgets to use it on her way through the kitchen to her morning shower, throw her a couple of oven mitts. I'll bet she gets the hint.

DEAR ABBY: Hi. I'm writing about the relationship between my dad and me. I'm 13 and my parents are divorced. They are now married to different people.

My dad forgot all about me for the first five years of my life. I finally got in touch with him and visited him for a few weekends, but now he doesn't answer my phone calls. He won't talk to me because he lost his job and owes almost $1,000 in child support. I think he's afraid to answer my calls because he thinks we're going to cuss at him about the child support, when all I really want to do is talk to him.

I've tried writing to him, but he doesn't write back. What can I do besides calling him or writing him? Please give me your advice. -- LONESOME TEEN IN RIVERSIDE, MO.

P.S. My stepdad hates me. I'm not comfortable with him.

DEAR LONELY TEEN: Sometimes people become parents before they're completely grown up themselves. Try to be patient with your father. Having lost his job and fallen behind in his child support, he may consider himself a failure and be ashamed to face you.

Write him one more note and say: "Dad, I need you to be part of my life. Just hearing from you is more important than money. I love you." Then cross your fingers. If you don't hear from him, the fault is his -- and it's no reflection on you.

Abby shares more than 100 of her favorite recipes in two booklets: "Abby's Favorite Recipes" and "More Favorite Recipes by Dear Abby." Send a business-size, self-addressed envelope, plus check or money order for $10 (U.S. funds)

to: Dear Abby -- Cookbooklet Set, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included in price.)

DEAR ABBY: My boyfriend, "Ricardo," and I have an ongoing dispute over money. He does not save or plan for the future. He thinks that if he wants to buy something, I should provide him with the money.

Ricardo quit his job before finding another, and I have ended up paying his living expenses. Several months ago, I loaned Ricardo money to buy a car. He's repaid half but still owes me the balance. He's borrowed more money since then to buy a present for my birthday.

My baby sitter quit last week, and Ricardo offered to watch my son until I find another sitter. When I told him I was unable to pay him the full amount I had paid the sitter, he became angry and accused me of never helping him or ever loving him. He says I am taking advantage of his kindness because I am working and he is not.

I have really tried to help Ricardo, but I think it's nervy of him to be asking me for more money when he owes me close to $1,000. What do you think? -- ALMOST BROKE IN BALTIMORE

DEAR ALMOST BROKE: I agree with you. Your boyfriend has turned mooching into an art form. Stiffen your backbone, tell him the bank is closed, and go on with your life without him. He's a bottomless pit.

DEAR ABBY: I am a 35-year-old woman. Two years after my divorce, I started dating a sweet man I'll call "Tony." He adores my 4-year-old daughter, "Emma," and she adores him.

Last week I learned I am pregnant with Tony's child. He's overjoyed. The night I told him, he proposed marriage and I accepted.

I also told my ex-husband, "Rod." He called me some vulgar names for getting pregnant before marriage. Now he threatens to tell Emma that what I have done is wrong. I know I made a mistake and I feel terrible. I don't want Emma to think it's OK to have premarital relations, and I don't know how to handle this. Any suggestions? -- TROUBLED AND PREGNANT IN MINNESOTA

DEAR TROUBLED: As vindictive as your former husband may be, let us hope he's not so twisted as to try to explain the dos and don'ts of premarital sex to a 4-year-old who doesn't yet know the facts of life.

Solidify your marriage plans immediately -- before your little girl understands the significance of counting to nine.

DEAR ABBY: My husband and I lived in a small apartment with our two young chldren in a bad part of town. When "Cousin Ramona" offered to rent us half of her large home in a nicer area, we jumped at the chance. It meant we'd be sharing the house with Ramona and another female renter, but we didn't mind.

Since we moved in, it has become clear that the female renter (age 19) is a real party girl. When I asked our cousin if any guys would be spending the night, she said no. Well, after only one week, our housemate started having a male visitor regularly for evenings and overnight stays. He also helps himself to our food. I am livid. I made a comment to Ramona about this "guest." She got uptight and said it was no big deal, and it shouldn't matter to me.

Well, Abby, it DOES matter. Our kids are 2 and 3 years old, and this isn't the kind of atmosphere I want them exposed to. Am I wrong? -- HELPLESS IN TACOMA

DEAR HELPLESS: Certainly not. You and your husband are responsible for setting the standards your children will live by. Waste no time in checking the classified ads for another place to live. The living conditions in your current dwelling are not as they were represented.

Dear Abby is written by Pauline Phillips and daughter Jeanne Phillips.

For everything you need to know about wedding planning, order "How to Have a Lovely Wedding." Send a business-size, self-addressed envelope, plus check or money order for $5 (U.S. funds only) to: Dear Abby, Wedding Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included.)

DEAR ABBY: After being divorced for nine years, I met a man I'll call Hal and married him six months later. He seemed caring, had a good personality, was good with children -- all the positive things you look for in a mate. I asked all the right questions about previous relationships, also drinking and drugs, etc. Hal told me he had been married once previously.

Two days before the wedding, I discovered he had been married twice. Two years later, it turned out that Hal had been married five times before he married me, and had lived with several different women between marriages.

He charged my credit cards to the max. I helped him to pay off past-due accounts, bad checks he had written and thousands of dollars he owed in child support. I went through drug rehab and counseling with him and supported him all the way. We are now divorced. He left me, saying he no longer loved me, and now, one week after the divorce, he has a new girlfriend.

I am furious that he treated me this way. Is there a law about how many times a person can marry? I feel other women should be warned before he takes advantage of them like he did with the six of us. -- USED IN JONESBORO, TENN.

DEAR USED: Although there is no law limiting the number of times a man (or a woman) may marry, there ARE laws against fraud. Failing to reveal the number of times one has actually been married may qualify as fraud. By all means discuss this serial groom with an attorney. It may set you back a few bucks, but a lawsuit could buy you a lot of satisfaction.

DEAR ABBY: My fiance, "Barry," and I are being married in the spring. We love each other very much and look forward to spending the rest of our lives together.

Ten years ago -- before Barry and I met -- he had a three-year affair with "Lucy," his brother-in-law's married sister. The rest of the family had no clue about their relationship. Barry ended it after he realized Lucy was never going to leave her husband.

Barry has been open with me about his indiscretion and our relationship is solid. Lucy continues to call Barry, even though he's asked her to stop. She has also called and harassed me, saying Barry will eventually leave me and return to her.

Our wedding plans are now being finalized. The invitations must be mailed in six weeks. If we do not invite Lucy, the rest of the family will wonder why. Barry believes it will raise suspicions if she is not invited. She has been very ugly to Barry and me, and I do not want her there. Please help. -- I DON'T LOVE LUCY

DEAR I DON'T: If you and your fiance would prefer Lucy not attend, don't invite her. Don't preoccupy yourselves with what your guests "might" ask; out of sight is usually out of mind.

If anyone is presumptuous enough to bring up Lucy's absence, just say, "We had our reasons," and change the subject.

THOUGHT FOR THE DAY: Choose a job that you love, and you'll never have to work a day in your life. (Submitted by Carl Young, Union City, N.J.)

For an excellent guide to becoming a better conversationalist and a more attractive person, order "How to Be Popular." Send a business-size, self-addressed envelope, plus check or money order for $5 (U.S. funds only) to: Dear Abby Popularity Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included.)