Credit Check in Head Office-Branch

Hi SD Experts

I am caught in a straneg situation

We have the concept of Head Office - Branch Office in Customer master i.e. in Customer Master 1064111, we have Customer 1064107 assigned in the HEAD OFC field

When Credit limit is set in FD32, we want Credit check to happen against A (Not Head Office). Hence, we change the CREDIT ACCOUNT to A (Default is B)

When we create Sales Order, Credit Check happens rightfully at 1064111.. But during VF01, Credit usage of 1064111 is reduced and is consumed from 1064107.. Is this Standard behaviour? When I have set Credit Account as A and it works for Sales Order, why not for Invoice?

Ajay M