@Redflash If I can make some suggestions for future castle upgrades:
a living quarters area for the harem and Cervius - adds harem interactions when not working (for example allow Soren, Zel, and Leif threesome, with all interactions having a watch and/or join options)
research zone (name pending) adds magic training, and can be used to change (increase or decrease) characters sexual traits (using magical essence most likely.
refinery add on (likely an upgrade to crafting room) refine ore into ingots and wood into planks.
essence distillery (likely another crating upgrade) distills milk product into essence (for example Zel's milk becomes storm essence, Alastor's maybe water?)
I absolutely love the mission room upgrade which looks amazing.
I hope to see more of this, it has been an absolute addiction from the moment I downloaded it.