Q) I am hurt and angry.

My husband was divorced from his first wife 10 years ago, when his daughter was 3 years old. We met and married more than a year later.

We have never lived close enough to see his daughter very often, because both he and his ex-wife are in the military and each has moved several times. However, we try for annual summer visits and have letter and phone contact.

His daughter's efforts at communication are my problem, even though we have sent stationery, stamps and stamped, addressed envelopes for several Christmases. One year she only wrote three letters.

We have never even received an acknowledgment for birthday or Christmas gifts or other little presents we might send during the year.

Because the buying and packaging of gifts has become my job, I said I wasn't doing anything for her birthday this year. My husband and I decided that a suitable compromise would be a contribution in her name to UNICEF. When she received this, her mother called to say that his daughter was very upset.

I relented at Christmas and made several garments. We sent some other things as well. We still haven't heard anything. We tried calling on Christmas but got a message that the phone was disconnected.

I have gone to the post office to make sure the package was delivered. What else should I do?

A) This will be hard to accept, but you can do most by backing off and giving your husband and his daughter the chance to know each other.

You've gone to a lot of trouble to shop and sew and send packages, but your good intentions weren't enough and they may even have gotten between them. Let your husband take care of the presents, no matter how busy he is. His choices may not fit as well or be as appropriate or as sensible as yours, but his daughter will know that he took the trouble to look for them, wrap them, address them and send them. Rightly or wrongly, she's sure to measure his caring by the care that he, not you, has taken.

You might think she'd know that he cares, but it is as hard for a child -- any child -- to know how much her parents love her as it is for parents to know how much they are loved by their children.

You can't expect a 13-year-old to show her love, however. At this age a child is more perceptive and knowledgeable, which leads her to be more reflective and withdrawn at times and more self-absorbed. On top of that, she's not going to reach out to her father -- even though she loves him -- because he is, in many ways, a stranger. Moreover, she is almost surely caught in the web of anger and doubt that wraps children of divorce, at least to some degree.

A feeling of abandonment makes any child hold back, but that's no reason for her father to hold back, too. She is his child and she needs her dad, like all 13-year-old daughters do.

You just can't stand on formality with a young teen-ager. Any parent, single or married, has a terrible time getting a teen-ager to mind her manners and in this case the mother probably doesn't try very hard, particularly if she thinks her ex-husband hasn't been attentive enough.

He needs to keep writing and calling. He surely has gotten in touch with his daughter since Christmas, but if the phone is ever disconnected again, he should follow up immediately and repeatedly to find out if she has moved -- and where -- or if she's in need. Each show of concern will make her feel more loved.

You can help in subtle ways, by making it easier for your husband to see her more often. An almost annual visit simply isn't enough. Because he's in the service, he can take a free military flight to visit her. Send $11.75 to P.O. Box 9, Oakton, Va. 22124 for Space A by Connie Connor, a thorough account of military travel on a "space-available" basis. Her bimonthly newsletter, Military Travel News, at $10.75 a year, keeps the information up-to-date.

If military flights don't appeal to him, help your husband find an understanding travel agent who will take the time to find him the cheapest flight to her town so he can see her for a few long weekends a year. If he can't stay at the base, the agent can book him into a discount motel so he has some of the days and early evenings to spend with her, getting to see her school, meet her teacher and her friends -- and getting to know her.

She'll begin to give him love and affection when she feels sure about his feelings for her. By then he can try to explain to her how much her letters mean to him and how love is a two-way street.

Once their relationship is more honest and secure, she'll be more eager to visit in your home and in time be affectionate with you, too, but again, you have to do the reaching first. Even so, it still may take some three-way sessions with a family therapist to bridge the gap between you.

It's worth the effort. Children need all the help and love and friendship they can get. By giving it to your stepchild you'll be helping the person who matters to you most -- your husband.

Questions may be sent to P.O. Box 15310, Washington, D.C. 20003.