To cite a volume originally published in a multivolume work and republished as part of a different multivolume work, cite the work as it appears in the republished multivolume series. For example, the Complete Works of John Ruskin is a multivolume series made up of thirty-nine volumes, and it contains a set of five volumes that are all titled Modern Painters. Those volumes titled Modern Painters were originally published as a separate series, and they were later included in the Complete Works of John Ruskin series and labeled as volumes 3–7 of that series.  To cite the first volume in that Modern Painters set, include the volume number that is assigned to the volume in the Complete Works of John Ruskin series, which is volume 3. For clarity, include the full number of volumes in the series in the supplemental-element slot, along with the title of the series: 

Ruskin, John. Modern Painters. Edited by E. T. Cook and Alexander Wedderburn, library ed., vol. 3, Longmans, Green, and Co., 1903. 39 vols., Complete Works of John Ruskin. Lancaster University, www.lancaster.ac.uk/the-ruskin/the-complete-works-of-ruskin/. 

If the original volume number is important to note, you could mention it in your prose or in an endnote.