Hello,
Due to the specificity of the "restriction", it would require a custom plugin.
Best would be to use "onBeforeOrderCreate" trigger ; check the cart content and authorize or not the rest of the workflow thanks to the " $do " variable in the trigger.
www.hikashop.com/support/documentation/6...#onBeforeOrderCreate
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.