Hi Sonia,
If you want to have different GL accounts for COGS for different company codes the simplest way is to use Valuation Grouping Code in OBYC. Create different Valuation Grouping Codes for different company codes. Assign plants from which you sell in different company codes to respective valuation Grouping Codes. And then in OBYC assign different GL accounts to VAX and Valuation Grouping Codes.
Regards,
Szymon