One of the most thankless positions one can fill in family life is that of the good friend of the parent who does not have custody of the children. However much the parent may love you on his own time, he will hardly be able to help, during the children's visits, slipping into the otherwise universal desire to cast you as villain.

Are you determined to go on with the life you and the parent normally lead, rather than casting it all aside to allow the children to dictate everything? How selfish and callous you are to the tender feelings of both children and anxious parent. Do you put aside all your own wishes and devote yourself entirely to their happiness? How selfish you are, using small children to promote your own romantic interests.

Do you set some rules, according to your best ideas of what is in the long-term interests of the children? How mean you are to expect discipline during the few free hours the children share with the parent.

Do you indulge them? How mean you are to subvert the child-rearing of the custodial parent.

Do you insist on being a part of the group? How egotistical you are to insert yourself into that fragment of the family. Do you absent yourself when the children arrive? How egotistical of you to avoid a difficult but important time in the life of someone you claim to love.

Miss Manners is reluctant to acknowledge that any etiquette situation is hopeless, but this one is close. Assistance is really needed from the children's parent, to defend this person's right to exist at all and to insist upon interpreting kindly meant behavior when all others jump to condemn it.

The parent, however, is generally emotionally overwrought during filial visits. Being a nonresident parent isn't easy either, and the natural instinct of children is to understand this and attempt to make it even more difficult.

If everyone would take to heart Miss Manners' advice about making such periods into periods of family life, with all its duties and pleasures, rather than into holiday-ish visits when constant treating is apt to begin to cloy, it would be better for all. The first step in playing this thankless part therefore consists of making the parent face what his hopes in regard to the children really are -- whether they are of establishing himself firmly as parent, or of outbribing and outshining the custodial parent -- and forming a plan to achieve them.

Concealing altogether a person who is an important part of the parent's life is, in Miss Manners' opinion, a mistake. Life after divorce is compartmentalized enough without that, and anyway, one doesn't want to run the risk of that person's being represented to the children entirely in the words of the former spouse. Nor should an unrelated adult interfere with a child's right to have private time with a parent. Even original parents, as well as stepparents, ought to know enough to allow individual children undisturbed time with an individual parent.

Especially when the time the children are there is limited, it is necessary to plan periods that are private between each child and the parent, as well as times, such as meals and some excursions or other activities, that bring the whole circle together.

The adults' interests should be considered too, but, without being unnecessarily explicit, Miss Manners suggests that the time for adults to be together in private is after the children's bedtime.

Dignity must be allotted to everyone at all times. Insisting that the child treat the friend of the family, or at least of one member of the family, with respect is of highest importance. Under no circumstances does Miss Manners accept emotional distaste, however understandable, as an excuse for rudeness. She would not think it necessary to add that the friend must also be respectful of the children, assuming that no adult worth tolerating would be otherwise, but this may involve some explanation of what politeness to children is.Condescension can be rudeness and so can the exercise of authority in those not used to combining this with tact.

What would family life be without the right to register complaints about one another? Nevertheless, Miss Manners is aware that this, too, is a no-win situation for the friend. If the children's behavior is criticized, the critic is told one has to make allowances for them and is made to feel callous toward the victims of a broken home. Let us assume, instead, that no one not genuinely interested in the welfare of children would consider it worthwhile to associate with them at all under these trying circumstances.

Q: I run a small business in my home, and have a friend who sometimes calls me when I cannot be disturbed. I usually say, "I'm busy right now, but can you call me back in half an hour?"

Her reply is, "No, you call me when you're free."

This happens quite frequently, and it annoys me because it's a toll call and I feel she should call me back if she wants to talk.

I dislike telephone chitchat, and it annoys me to have to pay to listen to someone else's. Whose responsibility is it to make the second phone call?

A: Yours, actually. Your friend understandably does not want to risk annoying you again with unfortunate timing, and one is not supposed to measure questions of friendship by toll costs.

Nevertheless, Miss Manners is in sympathy with your aversion to the custom of telephone visiting. Recognizing that it is firmly established as a convention of socializing, one must make special efforts to avoid it.

A gentleman of Miss Manners' acquaintance simply tells friends apologetically, "I'm afraid I'm just no good at telephone conversation." It gives him the reputation of being an eccentric, if not a half-wit, but, together with the courteous habit of issuing notes and invitations so that friends understand it is not a dismissal, it discourages them from ringing him up idly.