I figured it out...both sites were under the same domain, so I was able to use cookies to prevent repeated invite displays as well as keep track of shared page views between sites.
Already have an account? Login
Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.
Sorry, we're still checking this file's contents to make sure it's safe to download. Please try again in a few minutes.
Sorry, our virus scanner detected that this file isn't safe to download.