Subcontracting?

Subcontracting?

I know how to enter bills from subcontractors/vendors, but is there a way to apply that expense toward a project in the time tracking module?
I also know that you can enter a vendor expense against a project, but a couple of my vendors send me invoices that I want to be able to track as payables and presently, if I do that, I can't associated that expense with a project.
I wouldn't think it would be too difficult to add that option.