I am a grandmother of six. Of my four children, three are incredibly prompt in acknowledging gifts for their children, which is something I taught all my offspring. However, the youngest and his wife acknowledge absolutely nothing from anyone in the family.

It is causing great hostility all around, and my pointed hints do not seem to sink in. I hate to think of innocent children being deprived of gifts from Grandmother, but I feel insulted that no mention is ever made of what I do. I have a very limited income and the limits may become even smaller if normal etiquette is not observed.GENTLE READER - By Miss Manners' count, you managed to teach manners to three out of four children, which is not bad. Although your job should be completed, perhaps your grandmotherly sympathies will bring you out of retirement to perform this task yet again.

You need not - in fact, should not - criticize your grandchildren's parents in order to accomplish this. Of course, you need not continue sending them presents, either, since they do not seem to appreciate them.

But as part of your own relationship to your grandchildren, you can gently explain the dynamics of generosity. To give is a pleasure, but only if it is clear that one has given pleasure. It would be pointless to keep sending things to people who don't want them, or who appear, from their lack of satisfaction, not to want them.

Your next present to them could be a box of paper, pen and stamps, and the offer to teach them how to write thank-you letters by helping them write those due to other members of the family.

DEAR MISS MANNERS - I have three women friends who are married (I am not). We all enjoy live drama (which their husbands don't care for) and go to see it together, having dinner before or after the play.

I am so often mortified as they discuss their weekend plans. The worst was this past week, as they invited one another to New Year's parties, discussing times and places and who else would be there.

I am left feeling absolutely devastated. No invitation is made to me. It is quite clear that this is a married-only situation. I have listened to the same story when they planned summer vacations and other social occasions.

I know that if they realized how horrible they make me feel, they would be instantly apologetic. These are kind people. So I say nothing and keep on smiling.

But it is devastating, nonetheless. When I mentioned this to another of my friends, her response was that I was too sensitive. I still feel terrible.

GENTLE READER - Miss Manners is sorry not to be able to share your generous description of your friends as kind. Discussing social events in front of one who is not included in them is, of course, classically rude. But the callousness required for doing so constitutes cruelty, as well.

These ladies are also not very smart, are they? Does not one of them ever imagine that she could be widowed? Establishing a couples-only social life is a social transgression only too often punished by fate.

However, you have a jolly group there, and it is hardly Miss Manners' place to poison it. Let us instead concentrate on re-establishing manners.

You must, indeed, call the problem to their attention.

The other lady, who suggests that you are too sensitive, shows herself to be not sensitive enough.

The truly generous way to do it would be to invite them and their husbands to a party at your home. You are surely not guilty of segregating social life by marital status, and as you profess to enjoy their company otherwise, this would demonstrate the ridiculousness of their policy.

If you are not prepared to go that far at the moment, you may quietly say, "I don't wish to intrude on your private conversation," and withdraw. Embarrassing them is a necessary requirement for making them stop, but Miss Manners trusts that they will have the grace to apologize and reform.

DEAR MISS MANNERS - My friend, her husband and her daughter were all members of her brother's wedding party, but her 9-year-old son was not. She chose to put him in a tuxedo, which was slightly different from those of the groomsmen, with accessories matching her gown.

Needless to say, the bride called her up and told her she was not happy with this; my friend replied that the bride had no say in the matter.

I say the bride had a legitimate complaint. If she had wanted him in the wedding party, she would have asked him.

GENTLE READER - What we have here are two nicely matched sets of etiquette violations.

1. Tuxedos are improper dress for 9-year-olds, whether or not they are in a wedding party, but the practice of insisting that wedding guests be dressed in a different degree of formality from that of the wedding party is a ludicrous one.

2. Given that the wedding party was in costume, however, Miss Manners supposes that no one else should try to ape them. But a bride has no business complaining about the dress of her guests.

Can we call it a draw, have apologies all around, and get this family off to a better start?

DEAR MISS MANNERS - I am married to a man younger than I - by 20 years, to be exact - and often when we are shopping, or even at a social gathering, someone will refer to him as "your son."

I am shocked and appalled by this reference. Is there an acceptable way to respond? Certainly in this age of acceptance, there is a way to discourage people from this assumption.

GENTLE READER - Anyone who makes a guess at the relationship between two people these days - or any other days, come to think of it - is a fool. But the only polite way to point this out is to say coldly, "Are you referring to my husband?" or to have your husband say, "I beg your pardon - I am the lady's husband." Anything more in the way of discussion is bound to lead to the rationale for the mistake, which Miss Manners assumes you do not wish to hear.

DEAR MISS MANNERS - We are four lady friends, and three of us are going to take the fourth out to lunch for her birthday.

I said we should ask our guest where she would like to go. Number two said we should select three places and ask our guest which one she would prefer. Number three said we should choose the restaurant ourselves. Which of us is correct?

GENTLE READER - Miss Manners doesn't want to call any of you wrong, considering how nice your joint intention is. But she considers your own solution to be the most awkward. Without any guidance, a polite guest would feel obliged to choose a much more moderate restaurant than her hostesses had in mind.

Are you unsure about tipping? Miss Manners' pamphlet, "On Tipping," explains who should be tipped and how much. It is available for $1.50 from Miss Manners, in care of this newspaper, P.O. Box 91428, Cleveland, OH 44101-3428.

Feeling incorrect? Address your etiquette questions (in black or blue-black ink on white writing paper) to Miss Manners, in care of the Deseret News, P.O. Box 1257, Salt Lake City, Utah 84110. The quill shortage prevents Miss Manners from answering questions other than through this column.