DEAR MISS MANNERS: My sister is a deeply unhappy person, always on the lookout for some reason to be offended. Everyone in the family has always tiptoed around her and tried to read her mind, lest we failed to fulfill her unspoken expectations. We all struggled to be absolutely perfect in order to keep the peace and avoid her wrath.

Of course, it did not work. Somebody seeking reasons to be angry and bitter will always find them. One by one, she chose estrangement from all of us, though her hatred always burned hottest toward me and our mother.

Mom really struggled with the hurt and embarrassment of the situation. She was always a very private person and did not want to be the subject of gossip, so the situation was never discussed outside the circle of people who had been rejected by my sister. Only I knew what Mom was really going through.

Mom passed away recently, and my sister was delighted. She made phone calls to express her great joy that the old "B-word" was finally gone to hell, and to mock anyone "stupid enough" to mourn her passing. She also told insulting stories I am certain were untrue, simply to hurt the listener and tarnish Mom's image. She was brutal.

I heard all this from a couple of Mom's friends, people who loved her and helped her as her health declined. They had had no idea about the turmoil within the family, and were utterly shocked and greatly distressed. Aside from these friends, I have no idea how many more calls my sister placed.

Unsure what to do, I got out my mother's address book and began writing letters to each person listed about whom Mom had spoken to me. I told them every kind thing she had ever told me about them, every expression of gratitude I could remember, all the nice stories she told me. I did not mention my sister or ask if any of these people had heard from her.

I wanted to respect my mother's desire for privacy regarding this break in the family. I just told them who they were in my mother's eyes, in hopes that it might help heal any hurt caused by my sister's choice to lash out and "set the record straight" about my mother's true feelings and character.

However, I have hesitated to send those letters. Is it appropriate for the bereaved party to send such letters of condolence to friends and neighbors of the deceased?

GENTLE READER: That you propose making amends without criticizing your sister is admirable. And such letters from the bereaved are properly written, though normally in response to letters of condolence. Doing so is an excellent solution to these circumstances; people who express sympathy are gratified to be told how much they were valued by the deceased.

Miss Manners would certainly not have you follow your sister in disparaging a relative. But if anyone brings up her conduct, you can say, "I'm afraid she is troubled," and refuse to discuss it further.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: What do I do when guests bring their own guests to our house?

I am not a practiced hostess, so I plan everything beforehand: menu, dishes to use, tables needed, etc. I've had guests show up at the door with family members who "happened to be in town." I've had to add tables, bring down extra dishes and send my husband for takeout to provide enough food.

This has resulted in my being a complete wreck for the evening, thinking vengeful thoughts about the "generous" guests!

Is there a courteous way to handle this? I don't feel it would be polite to ask the uninvited to leave.

GENTLE READER: No, it wouldn't. They are most likely innocent parties, who have been assured that you will be delighted to include them.

So Miss Manners prefers to deal with the guilty parties.

"I'm so sorry you didn't warn us about bringing other guests so we could prepare for them," you should pull them aside to say. "Would you be so kind now as to help us out?"

They are then the ones you send out for extra food, and seat separately if there is no room for them at the main table. If they do not understand, at that point, how much trouble they have caused, they will when the people they brought rave about how welcoming you were to them.

DEAR MISS MANNERS: I would like your advice on how to respectfully correct individuals who insist on addressing me by my given name rather than my professional title, which is "Dr. Smith." I was always taught to address adults respectfully by Mrs./Ms./Mr./Dr. and their last name, unless specifically invited to use their given name -- a practice that I continue to this day.

Yet, even though I never introduce myself using my given name in the professional environment, I frequently am addressed that way by the parents of prospective clients. I also have noticed that my male colleagues are often referenced or introduced with their titles and last names, whereas the same people use given names for my female colleagues.

I am a licensed psychologist with a specialty in pediatric neuropsychology. I successfully completed three years of undergraduate studies, seven years of graduate school, a year of internship and two years of postdoctoral training and specialization prior to becoming licensed and starting my own private practice seven years ago.

I also identify as a woman and am a "mature" individual. I certainly feel that I have earned the respect of being addressed by my title. What would you recommend?

GENTLE READER: It cannot have escaped your attention that titles of any kind have fallen into disuse -- although, as you note, more frequently so in regard to women.

So while it is awkward to insist on one's own title, Miss Manners understands that it is sometimes necessary. And you needn't produce your C.V. in order to deserve it.

As your patients are children, you must be practiced in delivering instructions in a kindly tone. You should use that tone to say to their parents, "Here I am called Dr. Smith."

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: I often do the evening kitchen clearing and dishwashing for our household, and I do a thorough job. While working at the sink, I often wish to spit into the drain, but hesitate, wondering if it is appropriate. When I do spit, I am careful and it goes directly into the drain, so it doesn't contaminate the sink at all.

I'm uncomfortable, though. Could you please comment on the etiquette of this action?

GENTLE READER: Human saliva and kitchen cleaning should never meet, especially at the same sink -- however undetectable you think it may be. (And it is only a matter of time before you are caught and never trusted to do the dishes again.) Miss Manners suggests that you continue rightfully hesitating until you are safely in the bathroom -- behind firmly closed and locked doors and with the water running loudly.

DEAR MISS MANNERS: Once a solitary diner has been seated and served, does etiquette allow said diner to put on headphones?

Suffering from severe tinnitus makes background music, the conversations of nearby diners and the general hubbub of restaurants nearly unbearable at times. Discreetly inserting earplugs is my usual course of action, but noise-canceling headphones would be my preference. What does Miss Manners have to say on the subject?

GENTLE READER: She hesitates to say, since you probably will not hear the answer.

This would be the argument against your plan, as it will become increasingly frustrating for the waitstaff to ask how your food is.

On second thought, Miss Manners suddenly sees the benefit. All right. As long as you promise to take off the headphones when you ask for the pepper or the check, she will allow you to wear them -- if it is done discreetly and without repeatedly and loudly saying "What?"

DEAR MISS MANNERS: Many times when I am invited to someone's house or to an outing, they have also invited other people, but did not tell me. I only find out when I arrive. Or they will mention that one other person will be joining us, and leave out mentioning a second or third.

This also happens in reverse: when I invite a person to an activity and they bring along someone else without telling me.

Am I wrong for being upset by this? If asked ahead of time, I would always agree to additional people. I just want to know in advance. I sometimes ask if it will be "just us," but also feel rude about doing that.

GENTLE READER: One social violation at a time. It is nice, but not required, for a host to inform one's guests of any unexpected or additional ones. It is definitely rude, however, to go to someone else's house and bring a guest without first asking permission. It is borderline impolite if there is no host, but the plans were mutually made.

Certainly, a warning is always welcome. And since you seem to have been burned multiple times, Miss Manners will permit you to continue to ask any repeat offenders if it will be "just us."

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)