Usage-based approaches suggest that children gradually build abstract syntactic patterns, called constructions, through processes of abstraction and schematization from the input they receive. Bilingual children have the challenge of learning two sets of non-equivalent constructions when they build their constructicon. This can result in deviations from monolinguals, which are commonly referred to as transfer. Targeting the expression of the caused-motion construction, the present study focuses on idiosyncratic utterances, those that do not correspond to monolingual adult language use, in three different age groups (4, 6, and 8 years old) of German–French bilingual children in comparison to monolingual control groups. The quantitative analysis showed that idiosyncrasies could be found in both groups, but with significantly higher rates in bilinguals at all ages. In a qualitative analysis, idiosyncratic utterances were clustered into three different types: syntactic patterns, use of verbs, and directional phrases. Regarding the analysis of these types, the influence of French could be shown. In order to classify this linguistic phenomenon in a usage-based approach, we propose to consider transfer as a form of overgeneralization within the bilingual constructicon.