Bilingual homeschooling: how do you allocate time between languages?

One parent, one language at home. German with Dad, English with Mum. Dutch as the environment language.

Formal lessons in the weaker language only. The dominant language maintains itself through life. Protect the minority language first.

Weekly Dutch family for one afternoon - other homeschoolers in the neighbourhood. Social context preserved Dutch without formal lessons.

Subject allocation: maths and science in English, literature and history in German. Languages develop different vocabulary registers naturally.