Honestly it's kind of bs that they patched the game so that you literally can't save them both now unless you're some form of Lawful alignment. Thankfully that's where the Bag of Tricks mod comes in -- turn off alignment restricted dialogue! :p

I don't know if it was changed or if I had some bug or whatnot but I did not kill any of the prisonner and only had to fight 3 wyverns and 1 manticore, no owlbears at the end.