Isabelle “Sis” Lennon Miller, mother of the Lennon Sisters who starred on Lawrence Welk’s popular TV show in the 1950s, died May 1 from congestive heart failure in Branson, Mo. She was 85.The Lennon Sisters — Dee Dee, Peggy, Kathy and Janet — made their national debut with Welk on his Christmas program in 1955. The girls — then 16, 14, 12 and 9 — soon became one of Welk’s most popular acts. They split from him in the late 1960s, and eventually had their own television show with Jimmy Durante. Miller was the mother of 12, in-cluding one daughter who died previ-ously. Three of her sons and a daugh-ter-in-law are also entertainers singing in Branson, Mo., and a son-in-law and grandsons perform as a rock band.