DEAR MISS MANNERS: Who pays for our son’s birthday dinner?

My husband and I went out of town to celebrate our older son’s birthday. It was originally going to be us, plus him and his girlfriend. Through our son, we invited the girlfriend’s dad and his girlfriend (who we hadn’t met yet) to join us.

At the dinner, our son’s girlfriend’s dad insisted on paying. My husband wanted to be the host, and explained this. When we took the waiter aside to insist upon paying, we found out that the other dad had already given his credit card to the waiter. Without knowing this, my husband told the girlfriend’s dad that this was a 26-year tradition, but to no avail. My husband is offended now.

GENTLE READER: Well, tell him to stop it. In all probability, the girlfriend’s father’s motive came from concern that his party outnumbered yours -- and likely some embarrassment for the addition of a lady whom you had not met and who was not directly invited.

Miss Manners entreats you to persuade your husband that the intentions here were good -- and that the charm of this birthday tradition comes from those celebrating it, not the person financing it.

Should the relationship with this family continue, you may tell your husband to have a frank, but kind, conversation with the other father about who is hosting whom and when. Your husband will likely be very grateful for this man’s generous instincts when it comes to bankrolling a wedding.

DEAR MISS MANNERS: I am at a loss as to how to best respond to co-workers who knock on my closed office door. You see, I am a working mother with a breastfed infant at home and, as such, must use a pump to collect and store food for my daughter several times during the day.

I am fortunate enough to have a private office, so I can simply close and lock my door and continue to work while pumping at my desk.

However, it is a common occurrence for co-workers to knock and inquire as to whether or not they may enter to ask a question or discuss a work-related topic. I feel that ignoring them would be rude, but my gentle “I’ll be a few minutes” or “I’m busy at the moment” often seems to invite them to attempt conversation through the door -- or worse, leaves me opening my door (bottles in hand!) to find co-workers waiting for me to emerge.

Surely there must be a way to get the point across that I need a few minutes of privacy without announcing through a closed door, “I’ve got my shirt off! Leave me alone!”

GENTLE READER: You need a sign, although Miss Manners assures you that it hardly need be as explicit as you suggest. “Please do not disturb” will do -- and a few succinct words at the next staff meeting as to the general subject of what they might be disturbing should effectively fend off persistent and oblivious co-workers.

(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: Do you calculate the value of a gift on its retail price or on the actual price you paid for it?

I work for a designer and have access to high-end merchandise at 25 percent of the actual cost. I can gift someone a $200 handbag that I purchased for $50.

Now, I do budget how much I will spend on family and friends; it’s the not-so-close friends I have an issue with. If I allocate to spend $40 to $50 on such a friend, but buy her something that retails $120 (but costs me $30), have I shortchanged her?

The reverse gets me in trouble, too. My group of friends does a gift exchange at Christmastime. We set a fixed budget of $50 each. I’ll spend $50, but buy something that retails for $200. The receiver doesn’t complain, but some of my girlfriends in the group complain that I overspent, making my gift more valuable than theirs.

GENTLE READER: Calculating the value of a gift -- retail, actual, wholesale, discounted or bulk, or marked up, down or sideways -- is not an activity Miss Manners finds to be either delicate or rewarding.

Your friend with the $30 or $120 handbag was not shortchanged because (we hope) she values the gift as a thoughtful gesture coming from you, not for its fetching price on the open market. The dollar limit on your Christmas exchange does serve a purpose, which is to limit the expense of the gift-giving from becoming burdensome. Your discount has accomplished this, an explanation that your friends should understand.

DEAR MISS MANNERS: I work for a large library system in a major city. There is a central library that houses administration and customer service, as well as 33 branches spread out over the county.

The other day, a person fairly high up in administration sent out an email to all staff saying one of the library’s partners had generously provided several dozen doughnuts, and they were in the central library staff break room. As the closest branch was over a mile away, and many branches were as far as 30 miles away, I felt this was rude to the people that read about the free doughnuts of which they were unable to partake.

Later, another person at the central library sent an email out reminding everyone there were still doughnuts and INCLUDED PICTURES. I found this to be incredibly inconsiderate of anyone not able to drop everything and travel to the central library to enjoy the food. Am I wrong?

GENTLE READER: You are wrong in escalating the seriousness of the violation to “incredibly” and capital letters.

Miss Manners recognizes, without understanding, how seriously employees take offers of free food. But she doubts that either the originating administrator or the replying photographer intended for anyone to drive half an hour for a free doughnut. They addressed their emails to recipients invisible to them, forgetting that some would not be within walking distance. This was thoughtless, but is best ignored: Even a lighthearted correction -- ”Looks delish, but some of us work across town” -- is likely to be seen as petty.

(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 an American married to an Englishman who is a college professor, and who has lived in this country for about 35 years. I will be moving with him to England when we retire.

My husband, who is from a lower middle-class background like myself, has been knighted! He still answers his office phone as “Pete Smith.” He never corrects people in the way they address him. The name on his business cards is “Peter Smith, Ph.D.,” plus a string of other letters including his knighthood, but of course most Americans can’t make heads or tails of that.

I admire his modesty, yet, perversely, I want to be “Lady Smith.” Will Miss Manners allow me to get away with this? If so, how?

GENTLE READER: Unfortunately, honors do not come with instructions for use, but your husband has the right instinct. In class-stratified societies, such as England, it is considered, well, low-class to refer to oneself using one’s title. And in an officially classless society, such as the United States, citizens do not use titles.

That said, Miss Manners would like to indulge your amusing yearning. Perhaps your own field of expertise is 19th-century British literature, and you grew fond of its designations.

Her advice is to make a little joke of it: “Well, actually, that’s Lady Smith, but you can call me Pamela.” Or, “Technically, I’m a lady, so I try to behave myself.” Or, “Sir Peter, I’m afraid it’s time for us to go home.”

Someone is bound to ask you what you mean. Then you, too, can be modest, and say, “Well, of course it’s not something we make a point of, but we do tease Pete about becoming a knight.”

DEAR MISS MANNERS: The former office manager in the medical office that I work in has terminal pancreatic cancer. She is not doing well at all, sadly, and we are told she could pass any day now.

My co-worker is very close with her, and our former boss knows how much my co-worker loves to give out cards and how very important the birthdays of her loved ones are. Our former office manager’s birthday is coming up, and those of us in the office would love to let her know that we are thinking of her by giving her a birthday card.

However, we are uncertain as to what the correct protocol would be in a situation like this. Is it considered rude or disrespectful to show celebration of the birth of someone we care about when her life is so close to being cut short?

GENTLE READER: Cards are written by strangers. And while people may enjoy finding one that is particularly appropriate to the targeted recipient, or just sending a conventional statement with an illustration, these are form messages.

What you want to say to your co-worker is not a mere “Happy birthday,” which could indeed seem callous, but “We’re all thinking of you on your birthday, and we miss you.”

So Miss Manners recommends finding a pretty blank card and writing that out.

(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.)