I think they should Not be from a different association or region.
1. Refs aren't paid much. Traveling costs money.
2. Does the ACC tournament bring in Big 10 officals? Of course not. They put trust in their officials to do the right thing not just in the regular season, but also in the post season.
3. Bringing those in from another Association or region, area, etc kind of says the following...."we trust you 100% all the way up until now, but we have to tell you, we just aren't totally sure now that it's the semis."
4. Based on the above, I would argue no. No need to bring in officials except 2 conditions. It cant be a person from his or her primary school doing their own school, and the state of Va should have a cutoff criteria in grading (I assume it does). For example, if Region A only has one official that exceeded the minimum grading criteria for qualifying to officiate in the post season, then the other regions should get two more officials to officiate Region A. I assume there is never a year in which each region or association can"t find 3 qualified officials.