credit limit (AR Invoice + Sales Order)

Dear Experts,

We have a bit of a problem here, so here is the scenario:

Customer 1 has a credit limit of 100,000

He orders an amount of 90,000, then he orders an amount of 20,000. since it is a service order the approval procedure will not prompt and can be added to A/R invoice with a account of 110,000. so he had exceeded his credit limit by 10,000.

is there a way to active approval procedure by adding all open Sales Order and Open A/R Invoice?

i have seen some queries in the forum but it is not activating the approval procedure.

for your help please.

thanks!.