Changing the shipping condition in VA01 and VA02 .

My requirement is to find an exit which changes the shipping condition in VA01 before shipping

point and route is determined . The new shipping condition is determined form the ztable which has

the fields sa;es org , ship-to customer , transportation group , shipping point ,

(old) shipping conditio andnew shipping condition . Except the new shippinig conditin all other are key fileds.

I tried my best to find an exit but in VAIN . I am under the assumption that there is no exit to do this .

Can any expert help me to find an exit if there is any ?

Regards,

Vijay .