Hi,
Please check the documentation of the data element EGMLD_BSEZ which says,
Use
By specifying the reporting country, call up the VAT reg.no. stored in the master record. The reporting country is not stored in the line item. For evaluations, the reporting country can be derived from the first two positions of the VAT reg.no.
Ask your functional consultants abut the Substitution with User exit option to do the same.
Hope this helps.