Rosemary M., 55, spent two years caring for her father-in-law before he died. Now she is readying herself for her mother's inevitable move out of her city apartment into Rosemary's home in a suburb of New Jersey.

Rosemary's built-in support system is her husband and her five grown children, who still spend considerable amount of time visiting the nest in this close-knit family.

Rosemary can speak candidly of the loss of privacy and sadness in caring for the elderly parent. But she also speaks enthusiastically. "I find the elderly more interesting than any other age group. There is more variety in their experiences than we have ever had."

Rosemary is one of a growing number of middle-aged Americans who are caught in a generational bind -- but on the other end of the spectrum. After their own children leave the nest, they are faced with the chronic needs of their elderly parents. Many of these 50-plus men and women spend their retirement years as caretakers when their parents move into their homes.

Betty Thayer, a Maryland social worker who counsels families involved in four generations of child and parent caring, believes the situation is eased greatly if the elderly parent has time to absorb the changes involved in having to move out of his home into his child's home because of failing health.

Even after the move to their children's home is made, "the older person needs time to work through losing their independence," Thayer says. "They need to mourn the loss of their former life -- their own neighborhood, their own furniture and especially their neighbors and friends.

According to Thayer, when the elderly parent loses his independence he loses a sense of power. But the middle-aged parent is also feeling a loss of independence. Consequently everyone "uses guilt messages."

Dr. Carol P. Hausman, who conducts a short-term (eight-week) counseling group for people with elderly parents several times a year, says, "A lot of times people take in a senior parent, or children, because they want to make up for something.

"They may need to get the love they didn't get in the past," she says. "If that's the case, it is trying to reach an impossible goal -- changing their parent. It's like turning the clock back."

It is easier on everyone concerned if there is a sense of "filial maturity," says Hausman, referring to "a responsible person caring for a parent and giving up the needs and wishes from the past."

Hausman says a major complaint is, " 'My parent is so self-centered. He/She never asks about me or my work.' Yes, they are self-centered. They are sick and frightened. The real healthy ones aren't usually home."

If it is clear the parent should come home, "remember nobody can be a nurse 24 hours a day," says Thayer. "You need to find your own needs and find time for your marriage on a daily basis. And you will need a support system."

Thayer recommends alternative living arrangements for the elderly "whenever it is physically possible." Some options:

*Homemaker services -- shared living with other elderly, or foster care;

*Personal Care Aid -- early-morning assistance sponsored by county agencies;

*Visitation programs such as Meals on Wheels;

*Visiting nurses.

Recommended reading: And You Thought It Was All Over, by Zenith Henkin Gross (St. Martin's -- Marek, 1985); Growing Old: A Handbook for You and Your Aging Parents, by David A. Tomb, M.D. (Viking-Penguin, 1984); You and Your Aging Parent, by Barbara Silverstone and Helen Hyman (Pantheon Books, 1981).