Exemption from service tax

X Pvt Ltd is exporting sofwares developed by Y Pvt Ltd. X Pvt is receiving the exports proceeds in convertible foreign exchange. so the exports are exempts from service tax in the hands of x pvt ltd. My question is whether y pvt ltd cab also claim service tax exemption since the softwares developed by Y pvt ltd but exports made by X Pvt Ltd.For claiming exemption by Y Pvt Ltd, whether it should receive payments from x Pvt Ltd in foreign currency. Whether both X Pvt Ltd and Y pvt Ltd can claim service tax exemption since same product is developed by one company and exported by another company.