Please note that your company being incorporated outside India would not be governed by GST laws. Your Indian consultant and as well as your Indian clientele on the contrary would have to comply with the said applicable laws.
In relation to this the invoice being submitted by you to your clients would not be applicable to any Indian Tax viz GST and the same needs to be complied by your client at their own end under Reverse Charge. Please check for the applicability of any US laws.
Further the fee charged by your subcontractor would also, for you, not have any GST implication and any compliance needs to be done by the subcontractor at his end, and no burden of the same would be applicable on you.
Please advise in case of any further clarification.
Thanks & Regards,
CA Aditya Dhanuka.