This paper explores family multilingualism through the lens of language ideologies upheld by parents within three Chinese transnational families living in Luxembourg. Following a linguistic ethnographic approach throughout the inquiry and analysis process, this study provides illuminating insights into the Chinese parents' language ideologies regarding their children's multilingualism in relation to multiple languages (i.e. Chinese, Luxembourgish, German, French and English) across various domains (e.g. family, mainstream schools and public linguistic space). Our findings indicate that diverse factors and rationales giving rise to these parental ideologies operate in a dynamic, interrelated way within mechanisms that integrate cognitive, social and discursive aspects. As such, parental language ideologies embody a mosaic of various cognitive constructs, shaped by varying dimensions and degrees of negotiation between human agency, social structures and discursive dynamics. This study argues that the parents' sense- and decision-making of their children's multilingualism arises within a globally, English-dominated, linguistic hierarchy, wherein the market-driven tendency has led to language commodification in a bid to maximise profits. The present paper makes an important contribution to advancing our knowledge about parents' roles as policymakers in engaging in family language decisions and children's language development within a transnational, highly multilingual context--Luxembourg--which involves three official, schooling languages on a nationwide scale.