A huge amount of data is everyday managed in large organizations in many critical business sectors with the support of spreadsheet applications. The process of elaborating spreadsheet data is often performed in a distributed, collaborative way, where many actors enter data belonging to their local business domain to contribute to a global business view. The manual fusion of such data may lead to errors in copy-paste operations, loss of alignment and coherency due to multiple spreadsheet copies in circulation, as well as loss of data due to broken cross-spreadsheet links. In this paper we describe a methodology, based on a Spreadsheet Composition Platform, which greatly reduces these risks. The proposed platform seamlessly integrates the distributed spreadsheet elaboration, supports the commonly known spreadsheet tools for data processing and helps organizations to adopt a more controlled and secure environment for data fusion.