Decide whether reputation should be tracked between accounts
From https://svn.torproject.org/svn/projects/design-paper/blocking.html#tth_sEc7.4:
We could track reputation between accounts (if you delegate to somebody who screws up, it impacts you too), or we could use blinded delegation tokens [5] to prevent the website from mapping the seeds' social network. We put off deeper discussion of the social network reputation strategy for future work.
There are some clear advantages to being able to link accounts. For example, if accounts are not linked, a simple attack would be to use one account to harvest tokens (invites) and use subsequently activated accounts to enumerate bridges.
However, we might not want to the liability of storing the social graph, in case the database were compromised. Perhaps we could consider an approach where links between accounts degrade (are removed) over time, or we only track a few links of the account chain.