Q: This one may stump you.

My boyfriend, a university professor, was invited for dinner to the home of a music professor. (I was out of town at the time.) He had a delightful time, and we would like to reciprocate and invite the family for dinner.

The music professor has a wife, two children, and an ex-mistress and her child, living under the same roof.

While we know Miss Manners would never inquire about the sleeping habits of such a household, we feel she might be a mite curious, as we were. But there is probably nothing prurient going on here. The professor is a refugee from a country that doesn't enjoy basic freedoms, and we suspect that housing his ex-mistress in this country is an act of charity.

What defines a household in this situation? (When my boyfriend ate there, the ex-mistress was out of town, as she frequently is.) We don't know enough about the family to know if they all socialize together outside the home. It seems that the ex-mistress's daughter is treated as a full-fledged member of the family, playing happily with her half brother and half sister -- the wife's children.

My boyfriend's solution is to go over to the house (they live just down the street) and say to the professor, "We would like you and your family to come to dinner ... " We would leave the definition of family up to him, and set the table with the correct number of places after he shows up with whomever.

How would you extend an invitation, Miss Manners?

A: Miss Manners regrets that the answer is not nearly as titillating as the question, which she enjoyed very much, thank you. She is happy to see you make the distinction, on her behalf as well as your own, between the legitimate feeling of curiosity and the illegitimate act of attempting to satisfy it.

You could, of course, entertain only the professor and his wife, without inviting the children or other, ah, appendages. But as you want to entertain the household, Miss Manners would only add to your solution by inquiring, "How many of you will be able to come?" so as to avoid a last-minute panic in the silverware cabinet.

Q: When placing butter on a piece of bread, does one butter the whole piece and then break it, or does one break it in quarters and then butter it?

A: If one is at table, one breaks off a small piece first, butters it, eats it, then repeats the operation. This rule is suspended if you are standing in the kitchen making sandwiches for the children's lunch boxes.

Feeling incorrect? Address your etiquette questions (in black or blue-black ink on white writing paper) to Miss Manners, in care of this newspaper.