DEAR MISS MANNERS: My husband will be having outpatient surgery with almost no risk to his life, but his recovery will be long and painful, with months of physical therapy and many restrictions on what he can do as he recuperates.

His mother, who lives several states away from us, knows that he needs the surgery, but does not yet know the date. She wants to be here when it is done.

The biggest problem with having her for a visit at this time is her dog, whom she refers to as her “favorite son.” She refuses to go anywhere, including our home, without him. She bought him a service-dog jacket and forces her way into any and all places she might want to go with him.

I like dogs, as does her son. That is, any dog but hers. The animal is hyper, aggressive and destructive. It never stops barking. It uses the upholstered furniture as a toilet and tears curtains off walls. It is always underfoot. It fights our dog, and has been the cause of trips to the emergency vet. It has bitten everyone in our family at least once.

She “disciplines” her dog with hugs and kisses and baby-talk scolding, but refuses to control it or allow us to do so. There have been many ugly scenes causing many hard feelings.

My husband needs peace and quiet. He cannot break up dogfights or risk a fall tripping over her dog. I need to be able to pay attention to his needs, not spend the time arguing with his mother and cleaning up the dog’s messes.

Since she has lied more than once about leaving her dog at home (the dog was “just too sad,” and we are “being mean”), we do not trust her to respect boundaries.

So, it seems that we must tell her that neither of them may visit. Is there a polite yet firm way to tell her this? She may be very obtuse about what she is doing to her relationship with her son and grandkids, but she is over-the-top sensitive about feeling rejected herself.

GENTLE READER: “I’m afraid that we can’t accept visitors while Horatio is recovering. We’ll let you know when the doctor says it’s OK for us to do so.”

Notice that while Miss Manners’ wording invokes your doctor’s authority, it does not strictly implicate him in a lie. Still, given your mother-in-law’s apparent obstinance, it would not be a bad idea to ask for something from him in writing.

DEAR MISS MANNERS: On occasion, at the gym, the person who starts using the treadmill next to me does not use headphones to listen to his/her device.

If I could come up with a polite way to let the person know that I would appreciate it if he or she left an empty treadmill between us, I think, he or she would gladly comply. But said the wrong way, I believe this request could create great antagonism. Is there a polite way to make this request?

GENTLE READER: “Oh, I love that song. I’ll have to put it on my playlist. But in the meantime, do you mind wearing your headphones so that I can listen to the ones I chose?”

(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 remember when cash registers were less automated, and the cashier was required to calculate and make change. The change amount now appears in the display, provided the cashier entered the correct amount offered by the purchaser.

How does a customer count the change without irritating those in line behind? I’m always tempted to ask, “Have you NEVER made a mistake? Is that why I should trust that this wad of money you are thrusting at me is correct?”

I doubt the majority of today’s younger generation knows how to count back change. Should that preclude them from verifying the amount, and letting the customer know it’s correct? Or am I turning into an old bitty?

GENTLE READER: Is an “old bitty” a biddy who is bitter enough to condemn a generation?

Miss Manners can think of three proper ways customers can verify the correct change without unduly delaying other customers: checking the receipt, estimating the amounts (recognizing that if you round to, say, $5, you risk being shortchanged), and learning to subtract faster.

She reserves her own frustration for cashiers who fail to notice discrepancies so great as to be nonsensical.

DEAR MISS MANNERS: One of my very good friends asked me a year ago if I could commit to being his date for two weddings. He is on a two-year program out of the country and, as it happens, he can no longer attend the first one, which is fine. The second wedding, however, is still a go, and he has reminded me multiple times to keep my schedule open (as I travel a lot for work).

I just had a conversation with him, and while we were catching up, I discovered (when I asked) that I am no longer invited if his recent foreign girlfriend is able to obtain a visa and attend the wedding with him instead. If she is not able to attend, he assumed that I would still want to accompany him.

Am I wrong for feeling that this is rude? I have already indicated that I do not want to attend at all, as I was not aware that I was a back-up plan. Please advise, as this is a close friend of 10 years.

GENTLE READER: At some point in their lives, everyone will issue an invitation to their B list -- whether to fit in among couples, to fill a place setting, or to provide a last-minute fourth for bridge.

Among truly close friends or relatives, it may be possible to have an understanding that filling in is a favor that will be reciprocated when the other person needs a maybe-date in the future. If it was understood that this was a convenience, rather than a date, you should not be insulted.

But as you have been asked to keep your own travel plans on hold for a long time, you may be excused for rescinding your acceptance. If your replacement is not able to attend, surely your friend can manage attending a wedding on his own.

(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’ve drifted apart from a longtime friend. She is recently divorced and has a new boyfriend, and unfortunately, we have very little in common at the moment.

Although we share a “friend group,” my husband and I have been left off of recent group invitations for events such as concerts and dinners. I’m actually OK with this, which says a lot about where the friendship is going.

Now we have received an invitation to a graduation party for her child. This feels selective in terms of the expectation of gifts, versus just having fun. Is it rude not to attend?

GENTLE READER: You are free to accept or decline as your inclination and your schedule permit, without fear of being rude. But if you now assume that an invitation from her can only be motivated by greed, the friendship is indeed over.

In your position, Miss Manners would have taken the invitation to mean that while the friendship is more distant, your friend still wished to include you in important life events.

DEAR MISS MANNERS: I have long wondered about those tiny straws that one receives in mixed drinks in restaurants and bars: They seem more suited to stirring drinks than sipping them. I always just take them out, and drink the beverage from the glass.

I can’t help noticing that I’m in the minority, though. Are you really supposed to drink through them? Am I being uncouth if I drink directly from the glass?

GENTLE READER: Etiquette is more forgiving of being overly, than underly, formal, and the straw is the tank top of eating utensils. Miss Manners has no objection to discarding it in the accompanying paper napkin, whether you are doing so because you need a stiff drink or because the effort of pulling liquid through such a tiny aperture gives you a headache.

DEAR MISS MANNERS: During my 25-year marriage, my husband’s brother and his wife have looked down their noses at me and have treated me horribly. My husband acknowledges this; however, he continues to interact with them, stating that he does not want to end his relationship with his only sibling.

Now we have retired and moved to another state. My husband has extended an invitation to see our new home, and they are planning a visit in a few weeks.

I refuse to have them in my home, period. How do I address this? My husband refuses to tell them my feelings and does not want me to make the call. I want to be gone when they come to my home, away to a nice spa hotel. Is this the best way to handle the unwanted houseguests?

GENTLE READER: Sympathetic as she is to your predicament, Miss Manners cannot condone the contemplated rudenesses of uninviting your in-laws or being absent when they arrive. Your husband needs to talk to his brother. The likely outcome will solve your problem: Either the in-laws will promise to mend their ways (in which case, you must give them a chance to do so), or they will be insulted and refuse to make the visit.

(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.)