How Credit Limits will work with respect to National Account when i check (Base Credit Check on Consolidated National Account ) check box

I have 4 customers with credit limits 50 each and have National Customer with credit Limit 800.Now I have Checked the Checkbox (Base Credit Check on Consolidated National Account ) in National Accounts window.

Now I want to know how credit limit will effect to Parent or Childs?

Let child customers be C1-50,C2-50,C3-50,C4-50 and parent customer be p1-800 

so what will be credit limits of each customer(child,parent)  after check box check box in National Account and how it is calculated?

Please provide any good resources to learn more about GP as I am new to GP.

Also How (Base Finance Charge on Consolidate National Account) will work ?  

Thanks

Sandeep K