Complex sentence: The LMS renumbered them into a more logical series of 5600-844, and later most were again renumbered 25600-844 series in 1934/5 to make room for "Black Fives".
Split into simpler sentences: The LMS renumbered them into a more logical series of 5600-844. Later most of the class were again renumbered into the 25600-844 series in 1934/5 to make room for "Black Fives".