SAP BusinessObjects Web Intelligence allows you to change data sources from one universe to another universe. You cannot change data sources from a universe to a local data source.

With the Web Intelligence query interface, you can change the data source for your query when necessary.
Scenarios for Changing the Data Source
Changing the data source is useful in the following scenarios:
An organization can have a marketing universe and a sales universe, both based on the sales database. The marketing universe uses objects for companies, contacts, leads, and promotional efforts. The sales universe uses objects for companies, contacts, sales orders, and sales revenue.
The marketing managers want to know how many of the contacts you established during a promotional campaign led to sales within the six months following the campaign.
With appropriate access to the sales universe, the managers can make a query that retrieves the companies and contacts that participated in the campaign. They can also change the data source from the Marketing to the Sales universe, add the Sales revenue object from the Sales universe to the query, and filter to retrieve data for the six-month period following the campaign.