Hello Manel,
do not understand your problem...
As you do not have ADDR_SHIP attribute populated, default delivery address at SC item level comes froms user's default settings.
As in your case, this address is the location one, this means:
- delivery address from default settings is the location one,
- you have a specific developement which is used to change the default delivery address by the location one.
Default delivery address is linked to user context: if you want to change one of its value, check DELIVERY_ADDRESS_GLOBAL_FILL method from /SAPSRM/CL_PDO_SHARED_USER class.
But, by modifying delivery address, you will generate a new address number...
Regards.
Laurent.