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.)

DEAR MISS MANNERS: I have posed this question twice, and realize that you don’t want to answer. Would you mind telling me why women and children loudly say “mwah” when they kiss a person on the cheek? It is only done in this country and is a relatively new custom.

Also, since when do men insist on kissing women on the cheek instead of shaking their hand? It is done by both young and old men. I really would appreciate an answer.

GENTLE READER: Yes, yes, Miss Manners wants to answer. But this is not an emergency hotline, you know. It is true that she can spout any etiquette rule instantly, but there are situations where she thinks things over, as rare as that is in this Twitter-y age.

What has her musing is why she rather likes the “mwah” sound (and whether it shouldn’t be spelled “maaaaa”).

Cheek kissing itself, as an ordinary greeting, is relatively new in the United States, and not limited to males. If anything, they do less, as they tend not to kiss one another. And the rule, which nobody remembers, is that ladies are supposed to initiate the form of greeting, so it is their choice.

Back to the soundtrack: As this sound is made with the mouth open, it cannot be managed while the lips are planted on a cheek. Therefore, it goes with the so-called air-kiss, delivered just beside the face, rather than on it. To Miss Manners’ mind, that is a good substitute for the touch-kiss that not everyone welcomes from acquaintances.

DEAR MISS MANNERS: Is it traditional for the future bride to pick her friends as bridesmaids, or can the future groom suggest a family member?

GENTLE READER: Traditionally, it is the bride’s choice. But while it may not be traditional for her to take into consideration the bridegroom’s wishes, Miss Manners considers it a really good idea.

DEAR MISS MANNERS: My daughter-in-law bought me a designer purse for Christmas. I really do not like it and will never use it. It is not anything close to my style, and I know she paid a great amount of money for it.

How can I get rid of this thing without hurting her feelings? I am just sick about this, as I do not want to hurt her -- but on the other hand, I would be ill myself trying to use this monstrosity.

GENTLE READER: How often do you see your daughter-in-law? And how will you dispose of the bag when you decide, as you are on the verge of doing, that the pain of wearing it is stronger than any pain you might cause her?

Miss Manners would like to spare both of you. The only sacrifice she asks is that you keep it for a while, although that would preclude returning it to the store. This is so that if your daughter-in-law mentions it, you can produce it and say that you are saving it for a special occasion. That the occasion is enough time having passed for you to sell it or give it away need not be mentioned.

(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.)