Hi Mike. 
I think your problem is a variation on the ‘freelancer’ configuration that has been discussed many times here.
Lucy and I are close to a solution. We got sidetracked rebuilding my online store last week 
but I promise to you all that as soon as that’s done, today or tomorrow, I’ll spend a couple of hours a day documenting this until it’s done.
But, in summary, here’s what we’ve come up with.
I started typing it out and it’s too confusing unless I do it properly. Give me a couple of days to get back to you?