Hello,
In order to display the vendor name in the email "header", it requires some modifications in the HIkaMarket core (mail class).
The current code process the vendor name for each item but we're working on improvements in order to support the "cart limitation" setting and use another "template variable" to store the vendor name.
It would require further tests to be sure that it could be compatible with current templates and would not need special modifications in the HikaShop mails.
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.