`That's my boy!' Parents of candidates point to vital role of American `elders'. COMMENTARY

ONCE it was the children of presidents and presidential candidates who got all the attention left over from the great man himself. How the flash bulbs popped for Caroline and John-John romping on the White House lawn ... for Lynda Bird Johnson dating movie star George Hamilton ... for Amy Carter reading a book during a state dinner. The summer of '88 is rearranging the hierarchy within the pages of the first-family album, reflecting a demographic change that a French author has playfully dubbed ``le papy boom'' (the grandfather boom) and most Americans refer to in more prosaic terms as ``the graying of America.''

Dorothy Bush and Euterpe Dukakis, the mothers of the '88 nominees, may not yet possess the revered status of Britain's Queen Mum. But they are literally and figuratively in the picture this summer - the new definitions of a photo opportunity. Clearly the days are gone when more Americans knew the name of a president's dog than a president's mother - not to mention a candidate's father or even father-in-law.

There, in an orchestra pit high above the Omni stage at the Democratic convention in Atlanta stood Kitty Dukakis's father, Harry Ellis Dickson - former concertmaster of the Boston Symphony Orchestra - conducting ``Fanfare for Michael'' to cap off his long orchestral career.

There, too, looming tall and erect on the stage after Dukakis's acceptance speech was Sen. Lloyd Bentsen's father, Lloyd Sr., a man who still rises at 5 a.m. and puts in 10-hour days overseeing his vast land holdings in the Rio Grande Valley.

Elsewhere at the convention, Dukakis's Greek-immigrant mother, Euterpe, was charming reporters with stories about her ``sweet little boy.'' And earlier this month great-grandmother Dorothy Bush was photographed leaving church services with an extended family that includes Vice-President Bush's five children and 10 grandchildren.

Of course, this is not the first group of presidential contenders to have parents aiding their political careers. In 1960, Rose Kennedy campaigned for her son Jack. Sixteen years later ``Miss Lillian'' Carter, who had served as a Peace Corps volunteer while in her 60s, did the same for her son Jimmy.

But this year's presidential race marks the first time in recent elections that both the Republican and Democratic candidates have had a living parent. And more significantly, it marks the first time a sociological connection has been perceived between the first family and the American family at large.

Those parents, octogenarians Mrs. Dukakis and Mrs. Bush and nonagenarian Mr. Bentsen, represent a new, rapidly growing constituency, political and otherwise - what sociologists call the ``old-old.'' At the turn of the century, only 123,000 Americans were 85 or over. Today the over-85s number nearly 3 million. By the end of this century, their ranks will swell to 5 million.

So far the recognition of a gerontological boom has led largely to such playing with statistics - figuring out the actuarial tables for catastrophic health care (and projecting the taxes) while documenting the stresses of ``double duty'' care-givers in the ``sandwich'' generation.

Then, as if to balance all this gloomy accounting, the news media have hastily, and a bit hysterically, constructed folk heroes and heroines - grandfathers who run marathons, grandmothers who climb mountains.

What, besides pointing cameras at them, are we to do about our new upper-digits class? The main point gets lost somewhere between extremes - the latest TV special by George Burns and the nursing home.

It is hard for a nation whose youthfulness has been its oldest tradition to recognize that life and vitality do not wear numerals. The sight of a first family stretching robustly through the generations ought to help. It should certainly serve as a present reminder to the new occupant of the White House.

Sometime on the evening of Nov. 8, the nation will learn whether Dorothy Bush's son or Euterpe Dukakis's son will become the next president. Whatever the outcome, one of these men, as the son of an ``old-old'' mother, will bring to the Oval Office a firsthand sensitivity to the needs of an older constituency.

And whatever the outcome, one of these women will have the useful honor of playing first grandmother - make that first great-grandmother - to a young-at-heart nation still searching for models of maturity.