Here we have a very nice open source script for graphing DB schema.
What we would like to be able to do is to have an option there for the collaborative work.
The most reasonable way will be is to have add four buttons there:

"master schema" (this will be the official version of the schema modifying which will be password protected )

"load schema" (this will load the master schema or any schema that has been proposed by users so that anyone can alter it and then save it as their own version(pulls up a list of all schema people created to be able to load - if person then can modify it but he will be allowed only to save the schema as a new version - not overwrite the original one)

"save schema" (this will allow saving the modyfied version of schema with additional field for comments by the author). And as the new versions of the Master Schema become available they are being listed and available by clicking the button
(pulls up a list of all schema people created to be able to load - if person then can modify it but he will be allowed only to save the schema as a new version - not overwrite the original one)