[mavric]

Gatekeeper appears to be the perfect solution, as the group parent automatically grey's out if there are no children available. So for me it was like:

Project A

-Task 1
-Task 2
-Task 3 Parent
--Task 3 child 1 Waiting on email back (context "Waiting : Bob")
--Task 3 child 2 (context "Work : Computer")
--Task 3 child 3 (context "Work : At the Hospital")

And by right clicking the parent and assigning a waiting context, when I do my weekly "review/follow up on all waiting tasks" action, I get the groups parent showing and the gatekeeper task next to each other in the context view which is helpful.