Research on heritage languages predicts that contact-induced change is selective: Some variables shift while closely related ones remain intact. Fine-grained variationist evidence for this prediction, however, remains limited. We test it by analyzing object expression in Canberra Vietnamese, a community in which generational restructuring of subject expression is already documented. Contrary to the pattern found for subject expression, object expression remains systematically conditioned by Coreferentiality and social network language across generations, with only one localized generational effect: In second-person reference, Gen2 speakers shift from kin terms to pronouns. Read together, this pattern indicates that change targets particular variables rather than sweeping through the grammar. Examining multiple related variables within a single community is therefore necessary to capture the structured, uneven nature of change in heritage languages.

This study investigates the differential effects of language attrition in two diverse linguistic domains: verb placement and object expression. Linguistic phenomena at the syntax – discourse interface, such as object expression, have been shown to be more vulnerable to attrition than narrow syntax properties, such as verb placement. This study aims to test this hypothesis by analysing spoken data from Portuguese–German bilinguals who have moved away from the dominant German environment. The results show that the speakers who have lost continued German input after the age of eleven years exhibit difficulties regarding object expression in German but do not reveal any relevant syntactic deficits in the domain of verb placement.