Auri tribes are considered constantly at war with each other. I think it's within the bounds that a Kha tribe member (or members) could have been taken into the tribe. Perhaps not of their own will at first, but the Xaela tribes come and go and merge and split. You should have some leeway.
Or perhaps it happened after Othard fell to Garlean rule and they put aside their differences? You've got some leeway to work with.
Or perhaps it happened after Othard fell to Garlean rule and they put aside their differences? You've got some leeway to work with.
