Congrats on the interviews! I wouldn't worry too much about that. A change from 4 to 3 (or even 2) is unlikely to make a significant difference on their decision. And as far as I know, they employment verification does not include that info -- typically just your title, dates of employment and salary are checked. And I also think you have a really good explanation for why it changed since you applied. But if you're concerned about your schools not having all the facts, you could send a simple email with the update.
I had a quick question that's a bit unusual I was hoping to get some guidance on. I've applied to a number of schools in Round 1 and gotten a good number of interviews. On several of those applications, I had to list my number of direct reports, which at the time was 4 staff. However, I recently learned that two individuals on my team are going to be assigned to other duties due to some changes in my broader team's workload, which should happen relatively quickly. We're looking to backfill their positions, and already have one candidate in our pipeline that should start in the next few months. The other spot, however, will likely take until the second quarter of 2018 to find and onboard a replacement.
I'm worried that it is disingenuous to not update the business school's I've applied to as to this situation, as I know that direct reports are part of the evaluative process. I also believe (could be wrong) that the number of direct reports is one of the things that is checked during post-acceptance verification. I was thinking of sending those schools that asked for that information a note explaining the situation, but didn't know if that would be unecessary or make it seem like I was not being truthful the first time around. Any guidance would be helpful - thank you very much for taking a look.