A family of Microsoft word processing software products for creating web, email, and print documents.
If all the documents that make up the contract are based on the same template, take a look at http://www.gmayor.com/Boiler.htm which allows the storing of projects by folder and thus enables a selection of documents to be assembled from those folders. Documents based on disparate templates are less predictable to handle.
Another possibility is to have the various sections in the form of building blocks, but they are perhaps less easy to manage.