I've been thinking about this for a while and had to post it. (I'm still on the episodes from 2016 if what I'm saying is totally outdated).
If Jaela is just the reincarnation of Rhavar, she's just him. But if she's technically his sister, then her mom would have had to give birth to both of them. I envision that after Rhavar died, his soul immediately ghost teleported back into their mom's body and she instantly became pregnant with a whole adult Jaela who then popped out of her loins like a champaign cork. Thus treating her hip bones like a champaign bottle that just had an entire second champaign bottle pop out of it.