Ok I saw this movie on the Elvira show about 30 years ago on a Saturday night. It was an Australian couple who took in a blonde pregnant woman they met at the park while on a picnic. She had the kid a pretty blonde/ blue-eyed little girl the couple had 4 kids already and one was a baby. Blonde girl smothered the baby then killed the 2 boys when they went to a picnic. She pushed the oldest daughter Lucy out of a window and the mother STILL wanted to raise her. At the end the husband sees the pregnant woman again befriend another woman with kids. He chases them but loses them [which really makes no sense because he was running and they were walking and they were only like 30 feet away]. Anyway would love if somebody knows this goofy movie so I can watch again thanks.