In Sweden, Shobresvenska is very interesting…
Children are perfectly capable of switching between multiple languages. It does not create a problem for them.
In fact, a study on 6 to 8.5 year olds in a bilingual Swedish school showed that children used code switching as a social tool, especially during disputes (5). The children would switch between languages as a way to escalate the argument, and as a method of differentiating themselves from their opponent. Code switching provided an additional layer to the communication, beyond the words they were saying.