Mordechai Yosef Elazar Leiner,

The great-grandson and namesake of the author of the Mei HaShiloach, he moved his followers to Warsaw, where he became an influential leader of global Orthodox Jewry. He wrote books defending his father's innovations, especially regarding the dye of tsitsit, as well as a book of his own original ideas on the holidays and parshat hashavua.
Works on Sefaria