Abstract Heritage language research has predominantly examined immigrant communities where cross border relocation reduces input and typically renders the heritage language ‘weaker’. This study instead examines heritage Slovene in a non immigrant, border shift context, where speakers remain in place but are incorporated into a new state creating an ‘in situ’ heritage setting with different input dynamics. We compare two such Italian communities, Gorizia–Trieste and Natisone, which differ in the degree of schooling and broader institutional support for Slovene. Using a production task targeting Genitive of Negation and pronominal clitic placement, we compare heritage and monolingual speakers. The Gorizia–Trieste group benefiting from sustained institutional backing patterns closely with monolinguals, whereas the Natisone group shows restructuring in Genitive of Negation and elevated clitic omission, consistent with reduced input and increased processing demands. These results indicate that in border shift settings, strong institutional support can mitigate heritage divergence and challenge simple ‘strong vs. weak language’ characterizations, with some communities approaching balanced bilingual profiles.
Stepanov et al. (Thu,) studied this question.