A second filter is added to a WebI document in a burst. The Report Variable option is available for the second and any additional filters. BusinessObjects only supports Report Variable for the first filter. Values for any additional filters must be supplied by the InfoBurst user with either manually entered values or values from a Data Source.
The InfoBurst user interface (InfoBurst 2021.2 and earlier) erroneously offers the Report Variable option for additional filters. The option will be removed in InfoBurst 2021.3.