Credit Check Processing BSFN B4200420

Need to pass additional parameter to B4200420 - Credit Check BSFN from business functions calling it from Sales order entry P42101.  I find B4200310 - F4211FSEndDoc clearly calls B4200420 - Credit Check Processing internally.

However, Logs indicate also W42101D Confirm Sales Order  View Controller (B4210400) calls Credit Check Processing BSFN B4200420.  But when I check the c code for B4210400, I don't see the call to B4200420.  Request where in B4210400 is B4200420 called.

So my query is where in B4210400 is B4200420(Credit Check) called ?  When I look at W42101D_ConfirmSalesOrder - B4210400 I see the code as below.  But not sure if the logic for SalesOrderApplicationController is accessible ?