DEAR MISS MANNERS: Am I free to order what I want when someone asks me to dinner? When I am paying for myself, I order what I want, and am not concerned about the price. Can I do the same when someone else will be paying for the meal?

GENTLE READER: No. When your hosts invite you to dinner, they do not hand over their charge cards.

A good guest avoids the pricier items on the menu. Miss Manners waives this rule in only three circumstances: first, when the host is specific about ordering an expensive item (“Try the lobster,” but not “Order whatever you want”). Second, when there is a mutual understanding about cost and reciprocity (i.e., the host for a recurring outing rotates, and there is a history of how much the meals cost). Third, when you are trying to forestall offers of a second date.

DEAR MISS MANNERS: When I graduated from law school, I had a graduation party at my home, for which I mailed out invitations. Four of the invitees were complete no-shows; despite my request that they RSVP, they must have forgotten to send their regrets.

I’m subscribed to a new service from the post office that sends me digital pictures of the letters I’ll receive, before they arrive in my mailbox. A few days after the party, I received one such notification: an image of an envelope with my address handwritten on it. The return address was cut off. It was almost surely a note from one of the invitees who couldn’t make it; few people know my address, and fewer still send handwritten notes.

I’d always thought “lost in the mail” was a euphemism, but now, a few weeks later, this letter still hasn’t turned up. I’m at a loss. One of these four people must’ve sent me a note (or even a gift), and I don’t want to appear ungrateful. But I also don’t want to shame the other three no-shows by asking if they were the ones who hadn’t bothered to send a note.

GENTLE READER: What will they think of next? Miss Manners herself prefers ignorance to being teased with notice of mail that is not then actually delivered.

It does, however, provide a solution to your dilemma. You could write to all four no-shows explaining -- in a light-hearted manner -- the awkward situation in which you find yourself. But beware. Mention only “a letter,” not a response to your invitation, and certainly not a present. Better to ignore the entire situation than to send a note that appears to be soliciting a gift when one was not, in fact, sent.

DEAR MISS MANNERS: My wife has been trying to find out the proper placement of chairs after getting up from the dining table. Are they to be left back, or repositioned under the table? Does this change when it’s women only, versus when men are present?

GENTLE READER: Etiquette interests itself in many arcane points, but the placement of the furniture after people are done with it is not usually among them. So long as the chairs are upright, not blocking the exit, and in the same general area in which they started the evening, Miss Manners assures your wife that will suffice.

(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: At a professional networking meeting, I was talking with the person sitting next to me. I had never met her before, and I was delighted to find that we shared a lot in common in terms of the type of work we do, common employers in our careers and so on.

Another attendee, who was sitting at the table in front of us, started to intrude on the conversation. He was latching on to things that my new acquaintance and I were saying, then taking them in his own direction, interrupting us repeatedly, and generally making the situation uncomfortable. I think he might have been on the autism spectrum.

I tried to be polite, responding to his conversation in limited ways where I felt I should in order not to be rude, but otherwise tried to turn the conversation back to the person I wanted to get to know. Once or twice, she and I just continued to talk to each other, ignoring yet another interruption from our third wheel, who would keep talking as the two of us tried to continue speaking to each other.

How should we have handled this situation? If my assumption is correct, I don’t believe that he deserves scorn for his behavior, nor would I choose to be rude in return. But I’m not sure how to discourage this type of behavior in a kind way.

GENTLE READER: If it surprises you to learn that the answer is independent of the motives and medical condition of your interloper, then Miss Manners will remind you that a mannerly person treats even the rude with civility, and that the infirm generally prefer to be treated like people to being pitied.

The only way to change a professional networking event into a first date is to change your physical location. This can be done by suggesting you excuse yourselves and go over to the bar or by suggesting a follow-up meeting and exchanging contact information.

So long as you remain in place, there is no polite way to exclude another networker from joining the conversation. Miss Manners apologizes if she has read too much into what you hope will happen next, but her answer is the same even if she has.

DEAR MISS MANNERS: How do you fend off rude questions from co-workers such as, “That’s a nice sweater. Is it NEW?” They often look me up and down, scrutinizing every thread and every sleeve on my apparel, as they ask this question.

While I don’t mind compliments about my clothes, I do mind the judgment that follows these supposedly thoughtful remarks.

GENTLE READER: The advantage in buried criticisms is that you are under no obligation to dig them up. Miss Manners advises you to say only “Yes,” accompanied by your most wide-eyed smile.

(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 need some help on how to cut conversations short gracefully when acquaintances and strangers start going on and on about their intimate medical problems. I don’t want to seem uncaring and do not want to go around hurting others, but I am frankly fed up with self-centered people.

I am not close to these people, but I am about to start cutting them off with something like: “I am sorry to hear of your illness/misfortune, but I really can’t deal with hearing the details. Please rest assured I give you my best wishes, but I really must be going.”

Please give me something more polite!

GENTLE READER: Would you settle for something more effective (but within the bounds of politeness)?

In your most compassionate voice, say, “Please stop. I feel for you -- so much, in fact, that I get squeamish when I hear about illness, and you won’t want to be around me. I’m really sorry, and I hope you understand.” Miss Manners trusts that they will understand that the physical consequences of nattering on would be dire.

DEAR MISS MANNERS: Are there etiquette rules for when restaurants suggest how much to tip? Most restaurants these days are helpfully calculating various tip percentages and printing them on the check.

Typically they calculate 15%, 18% and 20%, but I’ve also seen 25%. In the past, I would calculate 20% and round up or down to a whole number of dollars. If the restaurant is helpfully suggesting 15% as a possible tip, is it rude to only tip that much?

GENTLE READER: Generally, it is not a good idea to take tipping advice from those expecting to be tipped. Often, ridiculous amounts are suggested.

But while 15% is a reasonable tip, Miss Manners hopes this will not discourage you from exercising your customary generosity.

DEAR MISS MANNERS: When I got married a little over a month ago, I did not register for gifts. We were surprised and delighted by some homemade presents and useful objects, some generous donations on our behalf, and some cards and cash.

But about one-third of our guests gave us nothing -- not even a card with well wishes. I was prepared for “no registry” to be read as “no gifts,” but I was surprised that so many attended without even bringing a card.

I’ve heard that wedding guests have a year to give a gift; do we need to wait a year to see if one is given? Or should we send notes thanking them for attending when we send thank-yous for the gifts and cards? I’m worried that will come off as a reminder to pony up a present.

GENTLE READER: Yes, it will, but that seems to be your intention.

When you decided to forgo a registry, Miss Manners fondly believed that you were that rare bride who does not believe her wedding to be an opportunity to shop at other people’s expense. And she was glad that you appreciated receiving thoughtful presents. Please do not spoil this by focusing on getting more loot.

Yes, wedding presents may be given -- or not -- within a year after the ceremony. But hosts do not normally write to thank guests, and there is no point in wedding guests handing over cards.

(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.)