Since we are unable to directly filter the item data using the subsidiary, we will have to use a modified version of the item query by joining the itemSubsidiaryMap table and subsidiary table to get the required results.
SELECT item.itemid,item.id,item.itemtype FROM itemSubsidiaryMap INNER JOIN item ON (item.id=itemSubsidiaryMap.item) INNER JOIN subsidiary ON (subsidiary.ID=itemSubsidiaryMap.subsidiary) WHERE subsidiary.id=${nsSubsidiary}