DEAR MISS MANNERS: I’m hosting a party with my best friend. We used a social networking site as our form of invitations; it’s a really informal event. My best friend’s ex-girlfriend saw it and has invited herself to the party. She said, “I saw that you forgot to add me so I added myself.”

I don’t want her at the party. There is a lot of bad history with her, simply because she creates drama. In the past, she has cried, fainted and even told others that she is contemplating suicide just to get attention.

Ever since my best friend ended things with her, she has been showing up at events that she wasn’t invited to, throwing herself at him (and other men) in sad attempts to win him back.

If she shows up at the party, she will create such tension that it will be ruined. How do I politely tell her that she is not welcome, and what do I do if she shows up anyway?

GENTLE READER: What does your best friend have to say about all this? It is not that Miss Manners mistrusts your intentions, but you are doing an awful lot of thinking and fretting on his behalf.

The problem with posting events on social media is that other people see them -- and either assume that they are invited, feel bad that they were not, or invite themselves. Although it is still impolite for the ex-girlfriend to have done the latter, a less public invitation would have eliminated the situation in the first place.

But here we are. If you can politely tell her that you think the party might be awkward for her -- or better yet, have your best friend do it -- that would be a first step. If she shows up anyway, you (or he) can reiterate. But if all that fails, and the party is in fact ruined, at least you will have learned that there are risks to making invitations visible to all.

Also, whether or not you deem it overly dramatic, if this woman is routinely crying, fainting and threatening her own life, someone should check on her.

DEAR MISS MANNERS: Every year for our birthdays, my husband and I receive a gift from a business associate. Previously, it was a small package of gourmet cookies. This past year, we each received very gooey caramels, which we cannot eat. We are in our 80s and have all our teeth -- along with pricey dental work.

How can we let them know their thoughts are appreciated, but we can’t eat the gift without hurting their feelings?

GENTLE READER: By saying “thank you” and then quietly passing the candy along to people with less pricey teeth.

DEAR MISS MANNERS: My daughter pushes food onto her fork with her index finger. Is it polite to use your knife for this purpose? Peas, for instance, are hard to eat with just a fork or spoon.

GENTLE READER: How old is your daughter? If she is under 5, Miss Manners will allow her to use a spoon on a non-precedential basis. But any older than that, and she will have to learn to chase them around with a fork like everybody else.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, gentlereader@missmanners.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: After asking my dinner guests not to bring any dishes, some still do. My question is what do do when Person A shows up with a dish, and Person B -- lovely, lovely Person B, who was polite and kind enough to take me at my word -- sees the exchange.

Person B invariably gets embarrassed and asks if they should have brought something. I usually say, “Oh, no! This is not a potluck. Person A just had a dish she really wanted to share.”

But inside, I am screaming, “No, Person B, you have manners -- unlike this completely overbearing person!”

The problem is that B is never comfortable with my answer, even if I talk to them later and explain what happened. It's a very awkward situation.

I’m not worried about getting through to Person A; they’re a lost cause. But how do I make things right for B, who is absolutely a dream dinner guest?

GENTLE READER: Short of dropping Person A’s dish on Person A’s foot, the way to demonstrate to Person B that they were correct to take you at your word is to go about your evening.

When you speak to Person B alone, add that you are most grateful for the courtesy of being listened to. Miss Manners is sure that that, coupled with your evident passion on the subject, will leave Person B in no doubt as to how you truly feel.

DEAR MISS MANNERS: We were informed of a friend’s daughter’s wedding plans recently, and were surprised when the formal invitation stated “black tie optional.”

The black tie notation was a double whammy for us, as we are a gay male couple. We have no intention of purchasing or renting tuxedos for this event, so the issue is whether to attend it at all.

My partner says that he would be comfortable wearing a black suit, and that the hosts and the bridal couple would also be fine with that, as black tie is merely optional. He also notes that what passes for "black tie" these days looks very much like an ordinary black suit with a few shiny bits and a black necktie, so we wouldn’t stand out much.

I maintain that “optional” means “requested,” and that the real instruction is, "Black tie is expected so that you can contribute to the atmosphere we are attempting to create. If you attend less formally attired, we will be disappointed and perhaps miffed, but you won’t be barred at the door.”

I am inclined to decline the invitation for fear of irking the hosts, who tend to be rather formal anyway, and so as not to disrespect the bridal couple, who clearly want the guests to help them create an effect on their special day.

Am I interpreting things correctly, or should I accept “optional” at face value?

GENTLE READER: Your partner is right about what passes for black tie these days. And while you each perfectly define a competing meaning of “black tie optional” in current use, Miss Manners does not know the happy couple, and therefore cannot say which applies.

She would take “optional” seriously.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, gentlereader@missmanners.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: I work in a fast-food restaurant, in which we only go by our first names.

Often, when customers decide that I am the cause of whatever is not going their way, they ask me for my name. My first name is clearly spelled out on my name tag, but I always say it for them anyway, as it is difficult to pronounce. It is an unusual name, and no one else in the store has it.

However, they also often ask for my last name, which I decline to give them. I don’t feel that it is any of their business. I just politely tell them that I don’t give out my last name. Often, they take this as rudeness on my part.

Am I in the wrong?

GENTLE READER: The reason stores use first names -- or first names and last initials -- on name tags is to balance two reasonable, but competing, requirements.

A customer is entitled to lodge a legitimate complaint through normal channels about inadequate performance by a salesperson. So the tag has to give enough information to uniquely identify the alleged offender.

But the salesperson also has to be protected against illegitimate complaints or unwarranted approaches outside of normal channels. This is why name tags do not include a full name, which could be used to look up and harass the salesperson away from the store.

From your letter's calm tone, Miss Manners likes to think that it is the complainant who is being unreasonable. But she nevertheless suggests you give this answer: “I am sorry that you are dissatisfied, but you do not need my last name to identify me to management. If you want to lodge a formal complaint against me, just give my first name and the time of my shift. I assure you that they will know how to find me.”

This response appeals to Miss Manners both for its politeness and because it calls out the customer's attempt to intimidate.

DEAR MISS MANNERS: While I have many friends, I enjoy traveling and dining by myself on occasion. When I ask for a table for one, the response is usually, “Are you all by yourself?” Or, “Are you waiting for someone?”

Then I am offered a seat at the bar, or a table near the restroom or kitchen door, which I decline. Once seated, it’s the same: “Is it just you?” Or, “Do you want to wait for someone before ordering?”

Is there a polite response to this, other than saying, “I’m all alone; isn’t that sad and pathetic?”

GENTLE READER: As the recipient of Gentle Readers’ mail, Miss Manners is all too aware of the deluge of rudeness in the modern world. But the transgressions of waitstaff -- who live in hope of generous tips -- usually take the form of ill-judged humor, not intentional put-downs.

The subtext you infer is most likely not intended to suggest that you are unpopular, but only to know the size of your party. This merits nothing more than saying you prefer a table elsewhere, and noting when you are ready to place your order.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, gentlereader@missmanners.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)