This study aims to explore how ethnic identity, linguistic ideology, and family capital work in interaction in shaping Korean-Chinese migrant families' multilingual planning against the backdrop of China's rapid urbanisation and internal migration. A model of investment (Darvin and Norton [2015]. "Identity and a Model of Investment in Applied Linguistics." "Annual Review of Applied Linguistics" 35: 36-56) was drawn upon. Data were collected via a questionnaire survey on 30 Korean-Chinese bilingual families in Shanghai, and semi-structured interviews and home visits with six focal families over a period of four months. The findings revealed a shift to Chinese and English and a suspension of Korean learning in the families. It was shown that the bilingual parents reconstructed their ethnic identity through linguistic socialisation, acquired hierarchical language ideologies, and made differentiated use of family capital. Moreover, when facing ideological conflicts and structural constraints, these parents attempted to sever the assumed link between language and ethnic identity, claiming that ethnicity is in the blood but not in the language. They made family language investment decisions guided by imagined identities they had for their children. The study contributes to the body of FLP research by eliciting a more nuanced understanding of how identity mediates the investment of different forms of family capital in different languages.