  Published: Wednesday, August 11, 1999   That Sela Ward and
Billy Campbell, stars of ABC's new romantic drama, "Once and
Again," are perceived as old "is absurd, but I guess that's the
reality," says co-creator Marshall Herskovitz, 47.  "It's funny
to me. Sela and Billy are so gorgeous, so utterly vital and
alive, there's no reason to think of them as old," says
Herskovitz, a Philadelphia native and Lower Merion High alum.
"As baby boomers, we're the kids. We'll always be the kids. I
see them (Ward and Campbell) as kids. It's so funny when people
say to me, 'Wow, they're middle-aged.' "  Ward, best known as
Teddy on NBC's "Sisters," and Campbell, star of the feature film
"The Rocketeer," play divorced single parents who awkwardly fall
in love. The first six episodes will initially air in the 9 p.m.
Tuesday slot now occupied by "NYPD Blue," which is launching
late.  After that, ABC's plan is to put "Once and Again" on the
shelf until "Monday Night Football" concludes in mid-January,
freeing up that 9 p.m. sl