Pardon me but, this game become really weird. I have a chance to play it before sometime ago, don't remember when exactly but yesterday I see it gettoing updated and I tried to play it again. CMIIW, before you could choose the age of both sisters, right? This feature is make the game quite immersive considering the dialogues and the scenes.
But I just play it again and when I reach the scene when the mother told that Katie was only 4 years younger than Emily (22), both the dialogues and the scenes before become well..., weird like I said earlier.
I know what Dev said in his post but honestly, you could be shooting yourself on the foot. But hey, it was just my opinion. Perhaps you have plan and tweak in the near future for this situation and the game back to become immersive again.
Anyway, good luck for you. I might come by and check again in the future.