[AtlUmpSteve]

When you login as an official on TheArbiter and go to the calendar blocks, it allows you to select which associations you are blocking at a given time (when you belong to multiple associations).

Whenever you have a published assignment (whether accepted yet or not) with one association, it automatically blocks another association from scheduling you at the same time. So, if you want to give general priority to one association, you need to stay on top of acceptances.