On a powerpoint presentation, like any action where you are using computer applications, it is important to save any important addition or change. So the answer to the question about placing an organization chart on a slide is that you must first update it, and then save it.
This would be the correct solution whatever addition you are making to a powerpoint presentation, even if it were only adding a couple of names to a list. The presentation must be completely clear to those watching it, so the organization chart should be fully checked for accuracy.
If errors are discovered then after saving the presentation, the errors should be corrected, the file updated and saved again.