We may have to back up a bit so we can get full context of what you need.
You mention “Report Builder”… are you trying to filter the report there (the SSRS report)?.. or do you mean in the “BAQ Report Designer” so the user can filter the report when they run it?
In either case, make sure the target field is included as a display field in your BAQ.
In BAQ Report Designer, you should be able to use that field as a filter, by adding it under the filter tab: