I'm going to start this one off real easy: This happens!
As you can guess, Wilhelmina sends out Frank and Lyman (why does she trust them to do anything?) to find the key, keeping Dorothy and Ozma stuck together forever. They all converged on a garden of keys where none of them seem to work. The only one that looks likely, Frank and Lyman snag it. So, Dorothy and Ozma try another approach, asking Dr. Pipt for his help. HE has a potion that should work, but it will turn whoever puts it on her fingers into a hideous beast. When both Ozma and Dorothy say they'll take it—causing the locket to part again and the girls to separate. Glinda floats in (her bubble barely squeezing through the window) and explains that their willingness to sacrifice for each other is the true key to happiness. Ozma tosses out the two lockets, only for Lyman to find them and give one to Frank, sticking the two of them together.
What struck me about this one was just how unhelpful Glinda was, acting a lot like she did in The Movie. She took off when the questions got complicated, only to appear at the end once everything was fixed and explain things at last. (Really, what good is this version of Glinda, anyway?) But the willingness of Ozma and Dorothy to sacrifice for each other rings very true and Ozzy.
On a pleasant additional note, another batch of episodes have popped up on my DVR, which means this series is going to go on for a while longer, probably into 2019. This is putting off my viewing of the next Oz series I have lined up, but I'm still enjoying Dorothy and the Wizard of Oz so much that I don't really mind.