Q. My daughter has just separated from her husband of less than four years and she and their 26-month-old son have come to live with us for a time.

Lately our grandson has become quite apprehensive if he isn't with or near his mother. I think he is upset by the separation and, of course, so is his father.

He had a very bad experience with a first divorce and was unable to see his daughter for years. She is just now, as an adult, in his life again and he is adamant that this will not happen with his son.

We all agree that my grandson needs to spend time with his father but how much? He wants the boy from Friday night through Monday morning every other weekend as well as every Tuesday and Thursday night. I think the child needs more consistency now and that every other weekend from Saturday morning to Sunday evening is about right, perhaps adding one night in the middle of the week when he gets older.

A. Father and son are experiencing real separation anxiety, but the needs of the child come first. After all, he lost his dad and his home and he doesn't know how or why or what will happen next. Your grandson acts as clingy as he did as a toddler because trauma makes children regress. Also, the apprehension that shows on his own mother's face also may be making him apprehensive: Children mirror their parents' concerns.

In the next few months he will probably get over his clinginess only to turn defiant, pitch fits, mope, get scared or play sick, partly because he'll be 2 1/2, but mostly because he'll be sure he caused the whole mess.

Your concern about the effects of shuffling on a young child is well-placed. Even one overnight a week with the nonresidential parent is considered too much until a child is 2 1/2, but daily contact is terrific if it's at all possible. A mother -- or a grandmother -- is no substitute for a father.

Ideally, your grandson would be with his dad all day on Saturday and maybe again on Sunday, so they could have big chunks of time together, and they would visit together every day, so their relationship stays strong and steady. His dad might pick up his son for breakfast and take him to day care, or pick him up after work and take him to the park or even go over to the child's house at night to bathe him and put him to bed, which could work if your daughter didn't hover around.

By 2 1/2, your grandson should be able to handle one overnight a week with his dad, working up to three overnights a week by the time he's 5 -- a schedule that should be acceptable for years as long as his father gets a healthy share of vacation time with his son and knows that every aspect of his child's life is as open to him as it is to the mother. He may not want to go to every school performance, teacher conference, soccer game or pediatric check-up, but he has the right to be as involved as he can be, in his own way and in his own style.

The father who takes part in his child's development not only experiences the joys of parenthood, but he also guides his child more deftly and even pays child support more willingly.

Your daughter will find good information in "Mom's House, Dad's House" (Fireside, $13), by Isolina Ricci, and "What Every Woman Should Know About Divorce and Custody" (Perigee, $14.95), by Gayle Rosenwald Smith and Sally Abrahms, and you'll profit by reading "Helping Your Grandchildren Through Their Parents' Divorce" (Walker, $12.95), by Joan Schrager Cohen. Custody issues are too tricky to handle alone.

Questions may be sent to margukelly@aol.com or to Box 15310, Washington, D.C. 20003.