If you have one active FINAL FANTASY XIV service account and multiple active FINAL FANTASY XI service accounts under your Square Enix account, the discount will be applied to one active FINAL FANTASY XI service account. The active service account that receives the discount is chosen at random, so you will not be able to select which service account receives the discount.

If you have multiple active FINAL FANTASY XIV and FINAL FANTASY XI service accounts under your Square Enix account, the number of discounts will be the same as the number of active FINAL FANTASY XIV service accounts. The active service account that receives the discount will be chosen randomly in this case as well.