Over the course of the past decades, patchworks of cross-border relations have emerged within and between the border regions of the Schengen Area. These patchworks, which vary in terms of density and intensity, often build upon longstanding formal or informal “bottom-up” relationships between civil associations, between families, municipalities and so on (see e.g. Crossey and Weber 2023; Opiłowska and Roose 2015; Sousa 2013), at times drawing from shared regional languages and dialects, customs, or shared experiences of war and conflict. The emergence of these cross-border networks is closely connected to a gradual widening of the field of foreign relations within post-war European institutions, from an almost exclusively national policy arena to a much more complex system of networks spanning across political-administrative levels to include subnational and non-state actors alike (Bache 2014; Marks, Scharpf et al. 1998 [1996]).