The new family was to be just like the original one, only better. The children would have two mothers and two fathers to love them. The parents' happiness with their new spouse would spread to all members of the stepfamily.. h

"Many people enter step relationships like this -- blissfully unaware of the jarring realities," says Jeannette Lofas, executive director of the Stepfamily Foundation in New York. "When feelings of hostility and conflicted loyalty surface, these people are in for a shock."

An estimated 50 million individuals are involved in step relationships.

"As the divorce rate spirals upwards," notes Lofas, "the number of stepfamilies increases proportionally. The nuclear family -- with a biological mother, father and child or children -- is no longer the norm. The moral, psychological, legal, economic and sociological considerations of the new stepfamily are mind-boggling.

"Becoming a stepparent is like being plunked down, a stranger, into the middle of rural China. All of a sudden you're speaking the wrong language and too many people are asking unanswered questions."

A self-described "super-step," Lofas became a stepdaughter in her early 20s and a stepmother in 1972, when she remarried. She recently became a stepgrandmother.

Her interest in the dynamics of step relationships started soon after she quit her job as an Oklahoma City TV reporter to become the "perfect stepmother" to her new husband's four daughters. Overflowing with love, she was shocked to discover that the girls resented her.

When her stepdaughters stopped talking to her, Lofas turned the problem into an investigative report -- "the only way I knew how to handle it." Her report became a book, "Living in Step" (with co-author Ruth Roosevelt, McGraw-Hill, $5) and a new life's work.

She founded the Stepfamily Foundation in 1977 as a clearinghouse for information and research on step relationships. Incorporating techniques gleaned from diverse disciplines such as Gestalt therapy and business management, Lofas teaches all-day workshops and has counseled about 100 families, or 400 people, struggling with the problems of living in step.

(She also has straightened out her own "step life" and describes her relationship with her four stepdaughters as "great.")

Each member of the stepfamily, explains Lofas, operates from a different point of view.

"Stepmothers pour out feelings of being used and used and used.Stepfathers speak of being strangers in their homes. Stepchildren describe feelings of never really belonging and being tugged in separate directions.

"Biological parents with children living with them speak of feeling split between children and mate. Absent parents communicate a sense of eroding loss and powerlessness over their childrens's development."

The biggest problem facing stepparents who seek Lofas' help is the deterioration of the marriage stemming from problems related to the children.

"People say, "We love each other, but our reaction to one another's children is breaking up the marriage.' We try to get them to take the 'love energy' of the new marriage and channel it into making the relationships with the children work.

"The most pervasive myth in a step marriage is that the stepfamily will function as does a natural family," she says. "It doesn't. It can't. The children are not yours and they never will be.

"In the traditional sense of marriage, the partner with prior children is not totally yours. One of the hardest things to accept is that somebody else always has a prior claim to that spouse or that child."

So far as the often-unrealistic expectations about stepparenting, Lofas says, "Having gotten out of a difficult relationship, having possibly been through a tough period of single parenthood, husband and wife expect wonders of the new marriage."

She suggests that couples pretend they're merging two companies. "Discuss beforehand the structures and procedures, and how the authority for carrying them out is to be shared.

"It helps greatly if the new family can start out in a new house. Planning for the house involves the whole family in the new adventure and adds a feeling of belonging. It is one of the most satisfying ways to go from 'mine' and 'yours' to 'ours'.

Establishing rules of the new house can solve the everpresent "but-my-mom-lets-me-do-it" situation. For example, if the stepchild complains that his mother lets him watch Tv until midmight, the stepparent might say, "I'll bet you enjoy that. However, in this house children your age go to bed at 11, so it's 11 for you tonight."

The stepparent role, cautions, Lofas, should be initiated slowly. "New stepparents, especially stepmothers, often come on like superparents. They rush in with goodies, avowals of love and excessive displays of parenting. They work so hard it spoils all the fun.

"Being a good stepparent requires a combination of knowing when to be active, when to take a moving, guiding, role and when to sit back, accept and be cool. Sometimes this means restraining the natural instincts, yet meeting the extraordinary obligations of step." CAPTION: Picture, Jeannette Lofas; Illustration, "I wouldn't be the person to ask. It seems I'm your lame-duck father." by Whitney Darrow, Jr.; copyright (c) 1976 The New York Magazine, Inc.