IMPLAUSIBLE it may have been, but last year's blockbuster "Home Alone" swept up box-office receipts because it appealed to the family impulse in all of us. It had a dynamite cast, a terrific director, punchy dialogue, and a clever conflict between the forces of good (Macaulay Culkin) and evil (the robbers). The boy defending his home against marauding villains appealed to the child's romantic heroics within us all. But what those heroics led to mattered even more - the reuniting of the family on Christmas morning. Whether reuniting families or making new ones, live-action Hollywood kid flicks this holiday season reassert the values of family and security for children. From the warm, fuzzy schmaltz of "All I Want for Christmas" and "Curly Sue," to the ecstatic excesses of "Hook" to the excruciating pretensions of "My Girl," we find adults as needy as the kids for home, hearth, and familial affection. Underpinning even the terrific adventure saga, "Star Trek VI: The Undiscovered Country," is the "familial" affection and clannish loyalties of the Star Trek crew. None of these is a great film, and one of them is downright despicable. But there is something to be said for the lot of them anyway - in all of them, the family is portrayed as a necessary safe harbor for children. The conventional kid comedy generally makes children out to be wiser than adults. The intrusive outsider - the mother's suitor or the father's mistress - is humiliated by the kids and sent packing by the parent. Both of these conventions surface in "All I Want for Christmas" and "Curly Sue" and they surely delight children. "All I Want" concerns two adorable children, seven-year-old Hally and 14-year-old Ethan, who want to reunite their estranged parents. In the unlikely tradition of "The Parent Trap," the two kids ensnare the parents on Christmas eve. Despite warnings from various critics that the film might give the children of divorced parents false hope, "All I Want for Christmas" really speaks to adults about the suffering their sometimes petty differences can cause their children. In this case, the parents love each o ther, they have only failed to communicate. "Curly Sue," made by kidflick master John Hughes, is as rife with deliberate sentimentality as any Shirley Temple film of the 1930s. In fact, "Curly Sue" is really a contemporary Depression-era comedy about a homeless man (James Belushi) and his adorable foundling, Sue (Alisan Porter), looking for a wife-mother and real family life. The wife and mother they find is, of course, the most unlikely candidate possible - a rich, icy lawyer (Kelly Lynch) who only needs to have her maternal instincts awakened. But as transparent as the plot is, as predictable as its outcome, Hughes makes it work for his young audiences. Updating many of the Shirley Temple themes to include a few off-color slips of Sue's tongue, a penchant for dishonest card games, and a certain street-wise con artistry in the child, Hughes still clings to the goodness of heart and the basic honesty of his characters. It's difficult to dislike the movie, however simple-minded it is about homelessness, because it tries so hard to fulfill the same function so many Shirley Temple films did in their day. The film encourages people to recognize the inherent value of children and to reassess their materialistic values. The same cannot be said for the execrable "My Girl as witless, pretentious, and offensive a film as is ever likely to be made in the name of childhood. "My Girl wildly dishonest advertising campaign suggests it is a love story about 11-year-olds. It is not a love story; it concerns a beautiful little girl's (Anna Chlumsky) attempt to cope with death. But to say that much is to distinguish the film beyond its merit. The scattered story is badly written and takes its trendy plot from pop psychology. It seems to the people who made this film that Americans don't have their noses rubbed in the issue of death often enough these days. The hare-brained, child-hating theory behind "My Girl" seems to be that watching America's favorite child star, Macaulay Culkin, die of bee stings will somehow make American children readier to cope with death in their own experience. The simple, common-sense reality is that "My Girl sitcom formula sheds no light on the experience of grief, the fear of mortality, or children's need for security. Young viewers unfortunate enough to stumble into this film unaware of its real content may be in for a nasty shock. A far better bet is Steven Spielberg's retelling of Peter Pan. "Hook" suffers from excess - excessive performances, excessive length, excessive sentimentality, excessive goofiness, excessive instruction. But despite its many problems, it offers a fine performance by Robin Williams in a remarkably complex reading of the charming story. "Hook" might have been a sublime work for the screen. The fact that it falls short is a pity. But it is still a decent family film (older children only, younger ones will be frightened of the violence) meant to remind parents (over and over again) how fleeting and precious is their time with their children. Maggie Smith as Granny Wendy (Wendy grown old) and Dustin Hoffman as Hook perk up the somewhat heavy-handed Disneyland quality of the production. "Star Trek VI: The Undiscovered Country" is a treat after the inanity of "Star Trek V." It makes a fine outing for families with teens (too violent for children) because, again, the values it promotes are peaceful coexistence, racial tolerance, and clan feeling. Its gentle "politically correct" message is remarkably good-hearted, with enough tongue-in-cheek humor to keep it lively.