what is the recommend way to set up 3rd party resources. I know they are to be setup as vendor. Lets say if on a project i have 5 3rd party resource from a single vendor how these are to be setup?

And of course, how can you avoid the issue of double cost? If you make your supplier to time entry and you post the time AND THEN you receive the invoice later it's obviously an issue. Let me know if you need to sort this out because I have an almost surely working idea but I've never tested it

Here in this case, we wont be entering time, only 3rd party resource would be entering time against a specific task. hence there wont be double cost.