GST on reimbursement claims

I have a few queries that I need help on:
We are a company providing professional services to companies in Training and delivery of workshops at their venue. All persons who execute services work on a contract with XYZ Pvt. Ltd. company. Does that make them a 'pure agent'?
While executing services, there are expenses for conveyance, food, transportation, goods/material purchased on behalf of the client/customer. We pay for this (including GST) to the vendor and then claim reimbursement XYZ Pvt. Ltd. company we have a contract with along with raising invoices to them for professional fees. Currently, we are being asked to raise GST over both, invoice as well as debit note (reimbursements). Is that accurate?