Laia Arnaus Gil is a post-doctoral fellow in Romance Linguistics at the University of Wuppertal, Germany. She wrote her PhD on the early acquisition of Romance and German copula and auxiliary verbs. She participated in a research project on code-switching in early bilingualism and co-directed the research project on early trilingualism. She is currently leading a research project on Catalan, Spanish and German as heritage (HL) and majority (ML) languages. She is also currently working on her teaching degree ('Habilitation') on the (early) multilingual acquisition of Romance attributive adjectives and the language-external factors promoting HL-competence. She is member of several research groups which examine linguistic variation in multilingual grammars, family language policies and the role of different factors for HL-competence.Amelia Jiménez Gaspar is a research assistant at the University of the Balearic Islands, Spain, where she received her PhD in Linguistics in 2021. During 2015 and 2016, she worked as a research assistant for a research project on early trilingualism at the University of Wuppertal, directed by Natascha Müller and Laia Arnaus Gil and funded by the German Research Foundation. In 2017, she obtained a grant from La Caixa Bank to enjoy a research stay at the University of Michigan (USA) with Acrisio Pires. She is currently a scientific member of the research project "Bilingual and Trilingual First Language Acquisition (BiTriFLA)" focused on Catalan, Spanish and German as heritage languages in Germany and in the Catalan countries, directed by Laia Arnaus Gil. Her research activity is focused on language acquisition and language development, taking into account the fields of sociolinguistics, bilingualism and trilingualism.