All iPads Switching Cellular between Air and Mini?

[I Need a Drink]

I'm buying an Air on Friday with Verizon, but I may also buy a Retina Mini at the end of the month, if I can get one, for the wife. I don't see the need to have both added to my plan and pay $20 a month for them. If I buy both with cellular, is is possible to add only one and then, if needed, switch them easily? For example if I have to travel for business have the service on my Air, but if she visits her sister, at some other time obviously, she can swap the Sim? Is it that simple, or would I have to call Verizon every time and add and remove each device from the plan as needed?