There are full pages about every main character at the beginning of the walkthrough, with a step by step guide for their events. For Kayelinth:
Character events sequence:
1. Feed her at the storage in Aldlyn until you have 30+ relationship with her. (Nude CG)
2. Talk with Kayelinth at the sleeping chambers to get the "Vegetable Garden" quest. You can find the “secret garden” by going up north at the right side of the castle. Don't cross the river. The “lost and found” center for the hammer is a normal looking soldier In the entrance of the castle (the map you get to by entering the castle through the big gate).
3. The next step requires 70+ relationship and you need to construct the bathhouse on the country overview map. (Oral CG)
4. You can now find Kayelinth's mother Jaylin in the Jewelry store in Thremten. After helping her in the search of her daughter, she'll move into the castle.
5. The next event requires that you're entered Minsk Harbour during the main story, that Mira had the event about her wings (second sex scene), and that your relationship with Kayelinth is at 100+. It starts with a dialog in the sleeping chamber, where Kayelinth will ask you to go to the Greencoast Tower. (First flight CGs)
6. Talk with Kayelinth to get the “Food Town” quest. Afterwards you can talk with her again in the castle for the next step of these events. (Tail masturbation scene)
7. Talk with Kayelinth again for her next event, the construction of her own farm. (First sex scene)
Bonus: Involved in a threesome with her mother Jaylin at the Amaranthe beach.