Hi,
A coupon is a percentage or flat discount for a single order. It is not possible to use a coupon partially.
By using a custom plugin (that need to be develop) we can imagine that another coupon can be generated when a coupon is used and is not totally used. The first coupon will be unpublished and a new one will be created (and display in the email, for example).
For you Gift Card automatic generation, you can use HikaSerial and his "coupon generator" plugin.
www.hikashop.com/support.html?id=139:hik...ugins-coupongen-form
It allow you to sell products which will create a HikaShop coupon after payment validation.
And thanks to the HikaSerial "attach serial" plugin, you can also include an image in the email, for this "Gift card".
www.hikashop.com/support.html?id=152:hik...ns-attachserial-form
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.