Modification of sales order GATP CIF

Hi Experts,

Material : M1

Sales org : 3000

Distribution channel : X1

Division :Y1

Material Master:

Material :M1

Sales Org: 3000

Distr. Chl :Y1

Material Group3 (MG3): 001

When we create sales order for the above sales area, the value of material group 001 (MG3) in the sales org view of material master will get updated in the additional data A in the sales order and this value is going to APO GATP for the sales order confirmation.

Requirement :

Instead of 001 (MG3 Value of sales org 3000 & distr.Chl Y1), we have to pass 005 (MG3 value of sales org 5000 & distr.Chl Y2) to APO GATP.

Proposed Solution : Modify the existing CIF to send 005 instead of 001

Can any one explain the steps on how to modify the CIF to send this value to APOGATP.

Thanks

Jay