We have a SQL Server 2008 Enterprise database with two different schemas, a locked one that we maintain and an open one that we allow outside development teams to add to and
You could look at putting your database under source control. Perhaps making each outside team take a branch or fork of your database. This gives you auditting of changes via commits and the ability to choose which changes to merge in and/or review/edit those changes before merging in.
Look at http://www.red-gate.com/products/sql-development/sql-source-control/ for one product that is available.
Combined with a solution like Github or Bitbucket that open up your source control repositories more directly to external contributors via internet.