User Exit during sales order cration for changing the customers kna1-aufsd

Hi experts,

our cusomers that do not order anything for a defined period of time get a special block in KNA1-AUFSD to "mark" them as inactive. Customers that do order after they have been blocked (=marked with a orderblock) have to be unblocked before the order can be created... thats ok for most cases; it is the standard behaviour.

I want to check if the cusotmer has the special order block in KNA1-AUFSD that marks it as inactive and change this automatically bevore the order creation is blocked due to the value in KNA1-AUFSD.

What userexit is bevore the

PERFORM TVASP_SELECT USING KUAGV-KUNNR
                           KUAGV-AUFSD
                           VBAK-AUART 
                           US_DIALOG  
                           CH_SUBRC.  

(in MV45AF0A_AG_PRUEFEN)

that checks the block?

Best Regards

Manfred