KIRSTIE ALLEY should make it from television to the big screen as long as she sticks to comedy. She's very good at it. She is particularly good at in ''Sibling Rivalry,'' a new comedy that was directed by Carl Reiner.
Reiner, who didn't do too well with his last few films, is back on top with this one. It's funny throughout. Some of us might have preferred a different ending, but the ending Reiner does use is certainly good enough.
Alley plays a neglected wife, married eight years to a doctor who pays her little mind. He is is very much involved with his family. She is barely acknowledged by them.
Her sister, a free soul, persuades Marjorie (Alley) to have an affair, which she does, with a man she meets in a supermarket. The man turns out to be less a stranger than he seems, and from thereon, coincidence piles on coincidence.
It would unfair to further divulge the plot's turns. It is enough to say that most of them work, thanks to Alley and Bill Pullman (''Accidental Tourist'') who plays a well-meaning salesman who becomes involved with Marjorie when her date for the night dies in their hotel room.
Sam Elliott is the one-night stand, and he may die from that mustache. You never saw a more expansive growth in your life.
Carrie Fisher is Marjorie's sister-in-law, Jami Gertz is Marjorie's promiscuous sister, Frances Sternhagen and John Randolph are Marjorie's parents-in-law, Scott Bakula is her husband, and Ed O'Neill (''Married . . . With Children'') is the cop who comes on to Marjorie's sister.
''Sibling Rivalry'' is a steady stream of comedy, most of it successful. Even when Reiner has his players do old gags, they work.
''Sibling Rivalry'' is showing at local houses.
*** A married woman has a one-night affair with a man who dies in the hotel room they are using.
CAST: Kirstie Alley, Bill Pullman, Carrie Fisher, Jami Gertz, Scott Bakula, Frances Sternhagen, John Randolph, Sam Elliott, Ed O'Neill, Bill Macy
DIRECTOR: Carl Reiner
RATING: PG-13 (sex, language)
TIME: 90 minutes