Thank you, we're happy to hear that!
We completely understand the desire to have unique interactions between the children and spouses, but as you can probably imagine, that's 4x37 custom scenarios, as a minimum (not 4x38, since you can't adopt if you marry a specific spouse), which isn't really sustainable. As you suspect, any type of gameplay/story based DLC would require a lot of everything, and we don't really have a lot of anything these days (as we enter year 5 of development, we're reaching a burnt-out-status on development and are getting quite ready to move on from making new content). Therefore, there will unfortunately not be any such DLC. The only content we will be adding are some remaining main events that will be released for free in 1 or 2 more updates. We'll think about adding some more hairstyles, outfits and hair accessories, but since they also take time and effort (especially outfits), we can make no guarantees. Sorry for the inconvenience!