[whpalmer4]

It's not a gratuitous constraint — how else would you indicate a task that requires all of the staff resources to be present?

It is a flawed system, however, as there appears to be no way to get both reasonable behaviors, and furthermore, it only applies to resources of the same type. If you set up a task with a staff resource and an equipment resource, OmniPlan will not ensure that both are available simultaneously! Maybe the answer is to turn half of your staff into robots :-)