Referral Trees

Is there a way I can track referrals through Qualtrics surveys? Here's an example:
Each person that enrolls in the study has a chance to recruit others for the study, and they get $5 for each of their referrals that end up being eligible and participating in our study. But there's also a possibility for others (who do NOT participate in the study) to refer people to our study, and they also get $5 for each of their referrals that end up being eligible and participating in our study.
I want to be able to track all referrals from one person back to that person through a form.
Right now, I have a study eligibility form and a referral form. For people who want to check their eligibility, they can indicate if they were referred by someone AND also indicate if they want to refer someone (in which case they will be routed to the referral form after completing eligibility). For someone who just wants to refer someone, they go to the referral form and put in their info and the info for who they want to refer.
Is this the most efficient way? Is there a way I can track referral trees in Qualtrics without linking people on the back end based on their name and the names of who they refer?