I'm trying to understand the request. So you have a connection via Web Data Connector to a remote data source. Upon connection, a local extract is built of the data selected upon connection. If you would like to limit the data that is brought back, this needs to be done in the initial connection. You could filter on the local extract data after the connection is made as well but I don't know of a way to use the data locally in the extract to recreate another WDC connection.
Anyone else able to assist?