DEAR MISS MANNERS: My wife and I are part of a close-knit group of five couples. We all socialize often, whether in our various homes or out doing some recreational activity.

One of our gentleman friends is truly a very nice person: friendly, considerate, good sense of humor and an animal lover (cats, anyway). However, at all of our social functions, his dress consists of shorts, a sloppy T-shirt and tennis shoes, usually without socks. That would be fine for a backyard barbecue, but that is his uniform for all occasions -- birthdays, graduations, anniversaries and even major holiday dinners where I feel something "nicer" is in order.

At special occasions, the host couples have gone to great lengths to prepare a festive dinner on nice tableware. I feel his dress is insulting -- not only to the host, but also to the honoree or the occasion/holiday itself. When we are dining at a restaurant -- not an old-fashioned "coat and tie required" place, but still semi-upscale -- he is again in shorts and a T-shirt, and I again feel embarrassed.

In every other way, as I said, he's a great guy. I wouldn't want to hurt or insult him. Any suggestions for a mannerly approach? Or should I just ignore this?

GENTLE READER: You cannot tell an adult to whom you are not related how to dress. And unless the event is black- or white-tie, you cannot really even politely put it in your invitations ("festive" is not a dress code).

Miss Manners is afraid that you will have to learn to live with it. Clearly this gentleman's other half has.

DEAR MISS MANNERS: My son is getting married soon to a lady I've not yet met, although we have spoken on the phone several times. My issue is that I do not want my new daughter-in-law to call me "Mom."

My son was very briefly married once before (now divorced), and that daughter-in-law called me "Mom" without an invitation to do so, at least not from me. I believe my son may have instructed her to do so. When we met, I said, "Hello, I'm Mabel Jo" so that she would understand I did not want her to have to address me formally as "Mrs. X."

How can I tactfully request that his new wife not call me "Mom"? It has nothing to do with her, I just don't like the practice.

GENTLE READER: Talk to your son. It sounds to Miss Manners as if he may have been the one who planted the "Mom" idea with the first wife. Explain that you would like the honor of asking his prospective wife to call you by your first name. Surely he would not dream of depriving you of that familial moment.

If he protests that he finds "Mom" to be more intimate, you may delicately point out that there were a lot of things that did not work the first time around. You are generously sparing him one of them.

(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 am usually good about thanking people. Now, I am flummoxed. A note or even a gift seems so inadequate for what friends have done for us.

In one case, some friends hosted my husband when he was cleaning out his mother's house, hours from home. They looked after the mail and even took my mother-in-law to get a COVID vaccination, which took them hours! The friends wouldn't even take my husband up on his offer to take them out for a meal in return.

Another friend did some professional work for us that I offered to pay for, but was told he doesn't work that way. (Years later, when we tried to continue the work, we were told he can't help us, so there may be bad feelings there.)

What do you suggest we do to thank these people who we cannot possibly thank enough?

GENTLE READER: Not thanking someone when no thanks will be enough is a natural reaction -- and one to be avoided at all costs. You may feel overwhelmed by their generosity, but from their point of view, you did not even care enough to acknowledge it.

Tell your friends the truth: that you were overwhelmed by their generosity at the time and cannot ever forget it. And that you feel terrible at having neglected to insist on paying for that professional work and that the very least you can do is to do so now, in addition to apologizing (note how Miss Manners snuck in that second apology).

DEAR MISS MANNERS: My niece was recently married for the second time, and as she had a formal wedding the first time, she chose to have a small, intimate ceremony in her garden this time. She invited her parents and her brother, but no other family members.

This seems reasonable for a second marriage. However, I found out about her wedding through a neighbor, who saw it online. I called her to congratulate her, and she said that she hoped to have a reception sometime in the future, to which extended family would be invited.

I don't know what to expect. Should I sign up for the social media platform on which my neighbor saw the news, just in case she announces the reception in the same way she announced the wedding? Is there a kinder way to announce a wedding to which very few were invited, and to extend an invitation to a future reception?

GENTLE READER: The problem with your niece's modest (and, as both you and Miss Manners agree, praiseworthy) approach to sharing her good news is that it is inconsistent with shouting it from the rooftop. Trust that if, and when, she does throw a reception, she knows where you live.

DEAR MISS MANNERS: My husband and I had houseguests wall-to-wall last summer -- some departing and arriving within hours of each other. We were amazed that people who stayed for several days did not offer to take us out to a meal during their visit.

We were constantly hustling chow, taking them to see the sites and providing entertainment. From them -- nada.

Is thanking your hosts with a meal an old-fashioned idea?

GENTLE READER: Apparently, from what Miss Manners hears. But it is still on the books, regardless of the numbers of scofflaws.

(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: Living in a city that generates massive quantities of plastic waste on a daily basis, I can't pass an overflowing garbage can or notice litter blowing down the street without thinking about where it will end up.

If I had my way, single-use plastic would be strictly limited to essential functions, such as in medical equipment or gloves to handle hazardous material. While plastic bag bans and paper straws are great steps forward, many businesses still seem to use way more plastic than is necessary.

I wish more businesses encouraged their staff to ask customers before adding, say, plastic utensils to a food order or a plastic sleeve over dry-cleaned items. While I would like to feel more comfortable asking business owners to consider making these changes, I'm not sure how to do it in a way that is polite and kind. I don't mean to cause offense, and the last thing I would want to do is annoy staff who are just doing as they're instructed.

When I have made requests to people in my own life to be mindful of their plastic consumption, they have responded defensively, leaving me feeling even more cautious about approaching strangers. As the ocean fills rapidly with our plastic waste, do you have any suggestions for ways to handle these conversations respectfully?

GENTLE READER: We live in a very imperfect world. Fortunately, many people feel compelled to right wrongs -- just not always the same ones.

But we can all agree that our cause is too important to give way to others' -- or to normal rules of decorum, like not haranguing strangers in the street. Miss Manners would have thought it was self-evident that doing so is counterproductive.

Make your case to people who are able to effect change -- at times when they are listening, and using language that will convince, not alienate, them. Such an approach will not improve things as quickly as you want, but it will do so more quickly than arguing over whose injustice is the worst.

DEAR MISS MANNERS: I found out through social media that my ex-father-in-law passed. My ex-mother-in-law posted a photo from a celebration of life that had been held for him.

My ex-husband's new wife forbade him from having any contact with me, but I am still friends with his mother online (although I am careful not to like or comment on her posts).

Would it be all right if I were to send her a condolence card, or should I just ignore it? There was no post made when he passed, just the one mentioning the celebration of life. Is it too late?

GENTLE READER: The opinions of current spouses regarding with whom you should, or should not, associate should be heard, if not necessarily always followed. Those of former spouses have no such standing.

Miss Manners does not mean to encourage you to do something merely to annoy. But sending a condolence note is a kindness to your former mother-in-law, not an intentional affront to your ex-spouse or his new wife. Explaining any passage of time is as easy as noting that you only recently became aware of her loss.

(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.)