[keiferski]

The thing is that Parent 2 already uses both languages on a daily basis, for work and for life. So in a worst case scenario the two just get mixed for the kid.

Avoiding one or the other isn’t really doable.

[fergonco]

I think it's enough to use one to address to the kid. If the other is present in the environment the kid will learn it to some extent. But I think there is value in simplifying the first steps with language. It's a hell of a struggle. And scary if it does not go well/quick.

I am not an expert, just what I've observed.

[throwaway7ahgb]

You won't have as much control here as you think. Try your best to be consistent as early as possible and hope for the best.

We are not as complex but we're trying this:

Mom (Russian/English): 100% Russian direct to baby, English to others.

Dad (English only): 100% English all the time.

Environment: English