This generally works if "Dynamic" and "Autoplay" are activated in the Queue settings.
I successfully tested it while playing an album : adding a single song to the empty queue, adding mutiple songs at one time, or adding multiple songs one after the other all worked well : the queue played its songs, deleted them once they had finished playing, and as soon as the queue was empty again the original track resumed at the exact position where the queue had been started with the first additional song.
The playing of the queue may be temporarily interrupted and resumed.
Perhaps I also found a bug : during one test I added an album to the queue, and once the queue had started playing, I stopped and completely shut down the player. After restart the queue performed without trouble, but once it had finished, the player didn't resume playing the original list that had been actice before the queue started. Bug or feature ? Perhaps this is related to the question whether the queue is supposed to be persistent :
EDIT : it might have nothing to with the shutdown of the player - I had the same effect after the queue had ended, when at the time the queue started the player hadn't been playing. I would have expected nevertheless the playlist that had been active befor the queue to become active again, playing or not playing. But perhaps that's more a feature then a bug - one could argue that in this case no auto-start was done, so the prerequisite for this new feature was missing.