select a.WStockid,a.WGroupid from STOCK_MULTIGROUP a where a.WStockid = <@WSTOCKID@>
and a.WGroupid in (select WGROUPID from IMP_LINK where WGROUPID = a.WGROUPID and imp_sourceid =<@SOURCEID@>)

UNION
Select a.WStockid,a.WReportingGroup1id from stock a where a.WStockid = <@WSTOCKID@>
and a.WReportingGroup1id in (select WGROUPID from IMP_LINK where WGROUPID = a.WReportingGroup1id and imp_sourceid =<@SOURCEID@>)