In this paper we present a novel approach to handle querying over a concept lattice of documents and annotations. We focus on the problem of "non-matching documents", which are those that, despite being semantically relevant to the user query, do not contain the query's elements and hence cannot be retrieved by typical string matching approaches. In order to find these documents, we modify the initial user query using the concept lattice as a guide. We achieve this by identifying in the lattice a formal concept that represents the user query and then by finding potentially relevant concepts, identified as such through the proposed notion of cousin concepts. Finally, we use a concept semantic similarity metric to order and present retrieved documents. The main contribution of this paper is the introduction of the notion of cousin concepts of a given formal concept followed by a discussion on how this notion is useful for lattice-based information indexing and retrieval.