Hello,
Would it be possible to have more details regarding the context and your issue?
I need to understand what "billing address" you're talking about, if it's something related to HikaShop or to HikaMarket; if it's link to the user/customer or the vendor...
You're asking where the "information is stored", but I need to understand what information you're talking about to be able to give you the right answer.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.