ALDA's role during Boost

[sjh]

I've read a number of times that on turbos the ALDA is only active in the pre-boost mode.

Are people certain this is correct?

I can operate my car such that the engine is at ~2200 RPM and I have 2" of boost or I can operate my car such that I have ~2200 RPM and 10" of boost. If the ALDA is not involved in fuel metering once the boost kicks in how does the pump know to deliver a greater quantity of fuel at the 10" of boost over the 2" of boost?

I'm just trying to understand. I don't claim to have any great wisdom on the matter.

Thanks.