How did Friedrich Engels prepare later volumes of Das Kapital for publication?

Following the death of Karl Marx in 1883, Friedrich Engels took on the responsibility of preparing the remaining volumes of Das Kapital for publication.12

Engels completed volumes 2 and 3, published in 1885 and 1894 respectively, by meticulously editing the uncompleted manuscripts and rough notes that Marx had left behind. This posthumous editorial work was a continuation of the close intellectual collaboration the two had maintained throughout their partnership, during which Engels had frequently provided Marx with technical and economic data and offered critical feedback on successive drafts of his work.13