Children are Pieces of Your Heart 1981 on netflix

A humble organ grinder is married to a barren woman. The pair would like to adopt a child but are too poor. Suddenly a miracle seems to happen: she’s pregnant. Unfortunately the baby dies and the man is forced, through hardship, to buy one from a chorus girl who wants to get rid of him. After a short time even his wife dies and the poor man brings up the child on his own, singing in taverns to make ends meet. The father and son’s humble life is upset when the real father of the boy reappears and wants his child back. The two men fight to get the custody of the boy.