Could we possibly declare a moratorium on scenes in which women demonstrate their inner wonderfulness by lip-synching to ''Stop! In the Name of Love''? Then again, even if they had cut that scene out of The Lemon Sisters, it would still leave the rest of the movie, which is the sort of earnestly wacky fiasco that makes you embarrassed for the performers. Why would Diane Keaton revert to playing a character who, on the neurotic-nerd scale, makes Annie Hall look like Ayn Rand? And what could have possessed director Joyce Chopra (Smooth Talk) to make a feminist-sisterhood movie about three middle-aged friends who persist in behaving like flaky, love-starved 12-year-olds? (I kept expecting one of them to start eating paste.) The Lemon Sisters gives female bonding a bad name. F

