My DD is trilingual. She constantly mixes the three, switching from one to the other. I'm mother tongue in language 1, DH is mother tongue in language 2. She speaks both fluently. Language 3 is of the country we now live in. I can't really speak very well, basics, so A2 max. DH is C1 in this language as it's close to his mother tongue and DD is fluent already as again it's close to language 2 and she's fully immersed daily in the school system. My question is, does she need to constantly use the 3 languages to remember them or will she lose 2 and 3 if she only speaks 1 for a significant amount of time? 