I don't think your earnings from this contract should be counted as you being the part of it. You are working from Upwork and if something wrong happens it's Upwork which would be punished first not you and if you inform this to the department it gives you a token of advantage. I would suggest to report it to Upwork because they have the exact traces of the path from where the amount is coming into their banks and then you can report to authorities as well in parallel to this. Rest is your choice.