Left-peripheral relative clauses (also known as correlative clauses) are widely attested in natural languages — in the Indo-European family, both ancient and modern, and outside of that domain too. Such is also the case of Basque, an isolate language spoken in South-Western France and Northern Spain, in which these Left-peripheric Free Relatives (LPFRs), are restricted to the Eastern dialects, i.e. those spoken in France, and the neighbouring subdialects spoken across the boundary, in Spanish Navarre...