Call Them Family Films : Does it really matter whom you know? Take a look at the children and parents of directors who are popping up on screen these days.

Filmmakers have put their relatives in parts big and small since the earliest days of the medium, but savvy readers of end credits have been kept particularly busy trying to match up directors’ and actors’ last names.

Here are a few recent examples:

* Director Chris Columbus cast his mother and three kids in bit parts for Fox’s “Nine Months,” which stars Hugh Grant and Julianne Moore. Three-year-old Brendan is a little boy on the beach, 6-year-old Eleanor is a girl taking a ballet class and the filmmaker’s mother, Irene, holds his daughter Violet, 1 1/2, in a scene at a toy store. Also appearing (as a paramedic) is Columbus’ father-in-law, Clarke Devereux, who has appeared in all of his films.

* In Columbia’s new Sandra Bullock film, “The Net,” director-producer Irwin Winkler provided brief roles for his wife, Margo, as a nosy neighbor, and his son, Charles, as a police officer. (Parts for Winkler’s sons Adam, as a computer nerd, and David, as a deranged transient, reportedly landed on the cutting-room floor.)

* Producer-director Jerry Zucker--who, with David, runs Zucker Bros. Productions--gave family members small parts in Columbia’s “First Knight.” Appearing are Jerry’s 7-year-old daughter, Kate, as a flower girl; 3-year-old son Bob as a little boy playing near birds; and his parents, Charlotte and Burt, as bread vendors. (His wife, Janet, is one of three executive producers.)

* In the Mexican film “El Bulto” (“The Lump”), producer-director Gabriel Retes (“Bienvenido Welcome”) cast himself as the star and his real-life son and daughter, Juan Claudio Retes and Gabriela Retes, as his fictional character’s offspring.

* For Universal’s “Apollo 13,” director Ron Howard cast his younger brother, Clint, a veteran actor, as a NASA Mission Control staffer. Also seen briefly are his father, Rance, as a priest and his mother, Jean, as astronaut Jim Lovell’s mother.

Casting kinfolk is “just a fun thing to do,” Columbus says. “I started when I did ‘Adventures in Babysitting.’ I put my father-in-law and my parents in the picture, and as I started to have kids, I just wanted to put them in little cameos, not really big scenes.

“I’m not really trying to push my kids into becoming actors. . . . It’s like wonderfully lit home movies.”

Another current family-ties trend is offspring producing or directing their high-profile fathers:

* Michael Douglas, 50, and Kirk Douglas, 78--in what would be their first time starring together--are developing “A Song for David,” a father-son drama to be produced through Michael’s company, Douglas/Reuther Prods., which has a distribution deal with Paramount.

* Director Fraser Heston, 40, is on location in Canada, overseeing his 71-year-old father, Charlton, in “Alaska,” a summer 1996 Castle Rock release. Heston portrays an evil poacher who helps two siblings rescue their father after his plane crashes. (The younger Heston started working in the business at age 3--months, that is--when Cecil B. DeMille cast him as baby Moses, while his father was starring in “The Ten Commandments.”)

Charlton Heston applauds Fraser for his “extraordinary eye” and for not treating him in an overly deferential manner like younger, greener directors might.

“He treats me as a performer,” the elder Heston adds, “and he says, ‘Do one more please,’ and ‘Do this instead of that.’ We did 11 takes on one angle yesterday.”

* Director-producer Charles Matthau, 30, is finishing Fine Line’s “The Grass Harp,” a November release that stars his 74-year-old father, Walter, as a retired Southern judge who strikes a romance with an aunt (Piper Laurie). Based on the Truman Capote novella, the film also stars Jack Lemmon, Sissy Spacek, Edward Furlong, Nell Carter, Mary Steenburgen, Roddy McDowall and Charles Durning.

The younger Matthau, who acted in several of his father’s movies, has been CEO-president of the Matthau Co., a production company, since 1989, found his father “a dream to direct. He listened to my suggestions, and he came up with some ideas of his own that were brilliant. It’s every kid’s dream to tell your parents what to do.”

But having a famous father can be both boon and bane. “You walk on the set, and people go, ‘Oh, well, the only reason he’s here is because of who his dad is,’ ” he says. “They tend to discount anything you might have done to get there.”

When filming of “The Grass Harp” began, the elder Matthau staged a practical joke. “The first time Charlie whispered to me, I pulled back and said, ‘B.S., I’m not doing that,’ ” he recalls. “Everyone burst out laughing.”

Other family-related endeavors on the horizon:

* “Up Close and Personal,” a contemporary love story starring Robert Redford and Michelle Pfeiffer, features the actress’s real-life younger sister, Dee Dee Pfeiffer, portraying her fictional sister.

* “Vampire in Brooklyn,” a Wes Craven-directed film starring Eddie Murphy, is co-produced by Ray Murphy Jr. (Eddie’s cousin), and the story is by Eddie, Vernon Lynch Jr. (Eddie’s younger brother) and Charles Murphy (his older brother).