DEAR ABBY: Recently my husband and I gave our daughter what we hoped would be an elegant wedding reception, followed by a sit-down dinner.

A cousin of mine brought her two young uninvited children, ages 4 and 6, who made a nuisance of themselves running around the cake table, screaming, laughing and playing tag while the dinner was in progress. I had to get up from my place at the table to ask them to please go sit with their mother.Because I did not expect the children, there were no place cards for them, but they sat down first, displacing two other guests for whom I had to find other seating! (We were short two dinners, but fortunately the caterers were able to handle it.)

Abby, please, please, please, tell your readers that if they receive a wedding invitation that does not specifically include their children, they should not assume that the children are invited. It is incredible that people actually need to be told this, but apparently they do, so be a "dear" and tell them. - BRIDE'S MOTHER IN INDIANA

DEAR MOTHER: I've been trying to get that message across for more than three decades. Each time, I have been bombarded with critical mail telling me that children "need" exposure to adult gatherings in order to learn how to conduct themselves.

I have also been called "an old fuddy-duddy" to suggest that uninvited guests of any age can drive a hostess's blood pressure up - and wear her patience down.

DEAR ABBY: When I read the letter from "Dog Tired," it brought back memories of the same type of situation I had years ago. I also had a barking dog in my neighborhood that nearly drove me crazy. The owner was a bartender who didn't get home until about 3 o'clock in the morning. Meanwhile, the dog barked at anything and everything he heard or saw moving.

I complained to the owner several times, to no avail. I was simply told that I was the only person in the neighborhood who was disturbed. I spoke to some of the neighbors, and they told me that they too were disturbed by the barking but they were unwilling to sign a petition of complaint, so I had to find my own solution.

I put a new two-hour cassette tape into my recorder and set it in my bedroom window when I went to bed at 11 p.m. I turned it on and just let it run while the dog serenaded me for two hours non-stop.

The next day, I took the recorder to my neighbor's home, turned up the volume and played it for him. Believe me, I didn't have to play it very long before he asked me to please turn it off. He then picked up the telephone and called a friend who lived in the country and asked him how soon he could come and get the dog. - DON IN CHULA VISTA, CALIF.

DEAR DON: Thanks for a doggone good idea.

CONFIDENTIAL TO UNDECIDED IN VICTORVILLE, CALIF.: Go to school and learn a trade. "He that hath a trade hath an estate; and he that hath a calling hath a place of profit and honor. A plowman on his legs is higher than a gentleman on his knees." - BENJAMIN FRANKLIN "How to Be Popular" is for everyone who feels left out and wants an improved social life. It's an excellent guide to becoming a better conversationalist and a more attractive person. To order, send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Popularity Booklet, P.O. Box 447, Mount Morris, IL 61054. (Postage is included.)