Television A Romantic from Ronkonkoma Moira Kelly plumbs the depths of Love in her new CBS series. by Diane Werts, Staff Writer DON'T TELL Moira Kelly that "To Have & to Hold" is just a romantic romp about two screwball lovers, a lighthearted way for CBS and its viewers to while away their Wednesday nights at 9. Ok, so this off-kilter TV hour might not match the drama and intensity of the former Ronkonkoma kid's imposing feature-film resume while she was still in her 20s - Roman Catholic activist Dorothy Day in "Entertaining Angels" (1996); wife Oona O'Neill in "Chaplin" (1992), the skating queen of "The Cutting Edge" (1991). But don't say "To Have & to Hold" isn't as relevant as that Day biography, for instance.  What in the world could be more germane to every person on Earth than love nurtured on a daily basis in so many tiny, telling ways? "I don't think there are too many shows on TV that touch that about relationships," says Kelly, dallying at the edge of a Los Angeles hotel garden where CBS is throwing a sprawling party during the TV critics' summer press tour.  Most CBS stars are in the thick of it, working the crowd, but Kelly is on the outskirts, working only a cigarette and a couple of wandering reporters who'd rather talk spiritual awakenings than show biz. "One of my favorite films of the year was 'The Apostle,' " the 30-year-old actress says.  "Why? Because it's about the man struggling with his soul, with right and wrong, with his own demons inside of him.  It goes beyond the religion.  Life is religion.  That's what it's telling you." And so is love, touching our souls in so many blissful, annoying, miraculous, everyday ways, which "To Have & to Hold" - set in an Irish neighborhood of Boston - goes to the heart of.  "It's very realistic in the ways that it deals with the smaller issues in life....Sean and Annie are wonderful, nurturing people who love each other, sometimes can get on each other's nerves, sometimes can be neurotic, but through it all will remain the best of friends," Kelly says of Jason Beghe's character and hers in CBS' witty roller-coaster romance. Maybe that's why the affection between Annie and Sean (Beghe played Jeffrey Lindley on "Melrose Place") leaps off the screen in a way few TV relationships do.  Sure, parts of this past week's premier episode were absurd: Like Kelly's public defender character would ever get assigned to an assault case that took place just across the street from her house and involved her then police detective fiancé. But Annie and Sean transcend all that blarney.  The sheer exuberance of their love is unwavering in the sort of way old movies were, where hell and high water and world wars couldn't stop two determined lovers from reaching each other's arms.  How do they keep the magic going? "When I think about Annie and Sean, I think about my mom and dad," Moira says of Anne and Peter Kelly, the Irish immigrants who had their daughter in 1968 in Queens, the third of six kids.  They took her back to Ireland for three years, then lived in Port Jefferson before settling in Ronkonkoma, and she attended Connetquot Senior High School in Bohemia.  Peter was a violinist with The Shannonaires and a music teacher, and Anne was a nurse. "My parents were equals," she says.  "My dad didn't overpower my mom, and she didn't overpower my dad.  They both knew what their jobs were in the relationship.  They both had their separate opinions, but they both knew the goal they needed to reach, and they worked at it together." The tight-knit Kellys influence the series' tight-knit clans.  Annie's sister is long married to Sean's brother, Annie and Sean marry in the first episode, and everybody seems to live on the same half-block in Boston.  In real life, Moira was still heading out on the weekends to see the folks.  (She lived on Manhattan's Upper West Side till the series demanded a July move to L.A.)  She had even come to the Island to warn them when she'd be getting a little nasty in David Lynch's 1992 big-screen "Twin Peaks" sequel, "Fire Walk With Me." "Either your mother tells you you're going to hell in a handbag or she gives you her blessing," Kelly says.  "I think I was told I was going to hell in a handbag, but she's okay about it now.  In my family there's a good sense of humor, and that's sort of the way we deal with things.  It's similar to the families in the TV show.  They deal with a lot of their daily problems with a sense of humor." And a wink and a sideways glance, all of which Kelly deploys in the series.  She's even got the look of those vintage-movie screwball dames - classic yet modern, sedate yet silly.  Kelly's heroines are old-timers like Katharine Hepburn, who could do it all.  That's why despite a thriving film career (including the recent "Dangerous Beauty,") Kelly decided to take the TV series plunge. Of course, it wouldn't hurt if she could make a few bucks doing it.  Kelly points to role models at this very CBS party, even the unlikely Suzanne Somers (now co-hosting "Candid Camera").  Somers has worked so long and hard on various projects (like the sitcom "Step by Step"), Kelly says, that "you think of the opportunities she has now to fund her own things - whatever she wants to do, she can do."