On the origins of Sraffa's equations

Giancarlo de Vivo suggests that the Sraffian equations come from Marx's schemes of reproduction, and that the inspiration was in a footnote from the editor, Karl Kautsky, in the Theories of Suplus Value. Here a letter from Maurice Dobb and Piero Sraffa to Kautsky, from 1929, asking to use his edition as the basis for an English translation (originals in Kautsky's archives):

De Vivo's views are discussed in a book edited by Massimo Pivetti, which is certainly worth reading (I have the Spanish edition). I never thought of this genealogy of the Sraffian price equations as being controversial, but I have been re-reading some discussion about Sraffa's contributions between Pierangelo Garegnani and Marxist authors (from the 1970s) as a result of the events related to the latter's ten year death anniversary, and it did strike to me that it is unclear to most Marxists how closely related the prices of in the Production of Commodities are with Marx's work.