I have a "companion" Global Service (GS) account and used my miles to redeem a ticket for a relative. I got different answers from the GS agents about whether I can use upgrade voucher for this award ticket. First agent told me yes as long as the voucher and mileages are from the same GS account; and the second agent stated that the voucher can work from any GS account. I don't have a GPU that I can test. Does any GS member have an answer? Thanks.