Reply To: Force free product coupon with single use coupon

[Soft79]

You can use the following WooCommerce filters for that:

woocommerce_apply_individual_use_coupon (must return an array with already applied coupons that may be kept)
woocommerce_apply_with_individual_use_coupon (must return a boolean whether a coupon can be applied while there are individual use coupons in the cart)