Set newly generated referral coupons to allow combination with other coupons. Review your promotion rules before enabling this.
Developer note:
Add custom PHP in a small custom plugin or child theme, and test it on a staging site before production. This example requires ongoing maintenance when extension APIs change.
functions.php
<?php
add_filter( 'automatewoo/referrals/coupon_data', 'my_store_referral_coupon_combinations' );
/**
* Allow referral coupons to combine with other coupons.
*
* @param array $coupon_data Referral coupon data.
* @return array
*/
function my_store_referral_coupon_combinations( $coupon_data ) {
$coupon_data['individual_use'] = false;
return $coupon_data;
}