Yes, Your Grace

This one is easier than the title suggests. You just have to ensure that your wife and youngest daughter survive the events that could possibly kill them. These events are: The Ritual for Aurelea and the Final Batrle for Cedani.

Cedani’s setup actually comes first and is far easier than Aurelea’s. Simply play the game normally until one day she shows up with a bear cub and asks you to let her keep it. Make the worst parenting decision of all time and let her keep a flippin’ BEAR with her. Wojack, as he’s called, will save Cedani from a hound at the end of the game automatically, winning you this achievement. Note! You have to actually check on her to get it. Towards the very end of the final battle, when Ivo’s forces break into the castle, you’ll be prompted to stay and fight, or go check on your family. GO CHECK ON YOUR FAMILY. You’ll find Celani and Wojack in your room with your wife (and heir if you’re batting 1000 here.), and a dead wolf at the entrance. Condition officially met.

For Aurelea, it’s a bit more complicated but not entirely difficult. All you must do is gather all the ingredients for the Ritual and perform it correctly. Since the Ritual itself is a whole other animal, I’m going to give the short version of its requirements here. The items you need are as follows.

Blue mushroom
Herb of Grace
Spell Book
2 Betony Oils
Mugwort Oil
2 Basilisk Eggs

The Mushroom can be found in your dungeon and the Book in the room Cedani hangs out in. Both can be retrieved at any time. The Herb is found by sending a general to specific areas on the map. There are three total spots, and each time he has a high chance to find it. I found it my first time all three runs I’ve played this game. The oils and the eggs are the most missable. During the lead up to the fight with Ivo, on certain days merchants will show up with items from exotic locations. One will have all the oils and another will have the eggs. The oils will come first. After gathering everything make sure you speak with Aurelea to alert her you are ready for the ritual. On the night before the final fight, you’ll perform it. Follow the witch’s instructions EXACTLY to succeed in both producing an heir and keeping her safe. She will tell you where to put each item, and how many go in each bowl. You must also read the book before hand and learn the incantations. You must chose the EXACT incantations at the right times for this to work. Again this is a very watered down version of the ritual itself because there’s honestly a more detailed guide that can be written about it for its own achievement. Just follow instructions and you’ll be golden. Don’t be afraid to reload a save if you have to.

Do both of these correctly and this achievement will pop after the final battle

In order to do this you have to not let Cedani or Aurelae die.
A full and fast achievement guide in the link below.