1. A method, comprising: accessing logical relationship information describing logical relationships among a plurality of user devices; generating, by a candidate scorer module, scores for each of a plurality of possible groups based at least partially on the logical relationship information and information about a first user device, but the scores not being based on any personally identifiable information about a first user of the first user device; selecting a first group from the plurality of possible groups based on the scores, the first group containing more than one user devices, including both one or more user devices that are not logically connected to the first user device in the accessed logical relationship information and one or more user devices that are logically connected to the first user device in the accessed logical relationship information; and adding the first user device to the first group.