credit limit

Dear All,

i have requirement in credit limit. i have 2 cust in one CCA, let say cust A and B.

i want to define credit limit like this:

Cust A has credit limit $ 500, cust B has credit limit $ 500, also i want to maintain that cust A and cust B cannot exceed $ 800 (credit limit $800 for both A and B)

can we do that, and how?

ur ans will be highly appreciated

Thx

Best Regard,

Hendry