I saved a household of 8 pets to library and now I can’t add them to game

So I started making different horses with the intention of saving them to my library and adding them to the world later when I finished building the barn lot to keep them. I got carried away and made horse after horse to add to different households later on and before I knew it I had used up all the slots, so I saved that household to my library. I completely forgot that the game doesn’t allow a household of only pets to be placed in world. But since the household is already 8 horses, it won’t let me add them to a 1 sim household. The game didn’t give me the option to transfer between households before placing in the world either. Is there any way at all I can retrieve these horses I created?