Yours, Mine and Ours (1968)

Navy officer Frank Beardsley (Henry Fonda) is struggling to raise his 10 children in the wake of his wife's death. Frank soon begins dating Helen North (Lucille Ball), a widowed nurse with eight children of her own. After learning of their similar situations, the two are reluctant to pursue a relationship. But with the help of a mutual friend, Darrel Harrison (Van Johnson), the two eventually fall in love and must decide about forming one big, unconventional family.