Is there a way to change the url that is sent out to track referals?

I want to track referrals per each user.

So if the author shares her content via sharethis, I would like the author's info to be appended to the sharethis link that is sent.

The user referal module https://drupal.org/project/referral does this to the forward module:
Forward module integration - enabling the module rewrites the urls sent by the Forward module so the user can get credit.