In the «Settings» tab of the «Referral program» section, you can specify how the commission will be distributed if the referral user of one partner followed the referral link or used the referral promo code of another partner:
One-time payment for an order using the last used referral code — the commission will be paid to the partner, whose referral link was used to place the user’s order.
Pay a commission to the main partner — the commission will be paid to the initial (main) partner, even if the following to the final checkout page was made using the link of another partner.