Gst issue in foreign holding and indian subsidiary

Co. A is a US based software tech co. and holding share of 99% in its indian subsidiary A pvt ltd. who is basically a back office for its US business.  For performing the back office operation A pvt ltd get fund from US as reimbursement of salaries and other expense in indian bank account.

Now the Questions are

1.what is GST implication of Export of service 

Reimbursement of services is at cost, no profit from holding co. is recieved, Pvt ltd is filing its GSTR 3B regulary and GSTR1 is pending due to this confusion.

2. if reverse charge is applicable how the transaction will flow from ITC and GST payment.

3. LUT for 2018-19 is generated but if it is not export of service because of related party how the indian co. will bear GST charges loss becasue it is in lakhs and no profit activity is performed in india.

Thanks in advance

Please answer .