sth simple but i have problem

[maniatis]

ihave one form with data from 4 tables that i have union them with a query.i mean the form is having data from 1 query. there are the following fields
location, agenname ,agentadress ,agenttelephone. i want to choose a location and brings me the records for the agent and agent details for the current location without choosing data from the other tables.
do u understand what am i saying?
please help!