Use joist tool multiple times on the same takeoff area?

Is it possible to use the joist tool multiple times on the same area? For instance, if I have a roof area that has both prefab wood trusses and purlins, am I able to use the tool to calculate both quantities using the same area takeoff?

Ideally, you'd be able to set the spacing, as well as length individually, so the grid tool doesn't quite work right if you have roof overhangs or gable ends.