She was a Polish farmer's daughter who emigrated to the United States, a maid who worked for a wealthy American heir, a third wife who inherited much of the Johnson & Johnson fortune after a sensational court battle with her six stepchildren. Barbara Piasecka Johnson, the widow of J. Seward Johnson Sr., heir to millions made from bandages, baby oil and pharmaceutical products, has died at age 76. Johnson was best known for a nasty legal battle after her husband's 1983 death, a feud that pitted her against his six children from two previous marriages. She largely prevailed, emerging with about $300 million from