Hi,
The best will be to use a "custom item field" (provided by HikaShop Business).
So when the customer will add a product in the cart, it will be able to choose the value for the custom field in the same time.
You can try the custom item field feature in our demo website.
demo.hikashop.com/
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.