Where do they go?

[Tjigra]

When you buy a horse, is there any system in what pasture or barn do they go into? I've been recently moving my horses around between my accounts a lot, and every single time I moved someone into my largest ranch, I ended up searching high and low before I found them. I understand that the game doesn't understand my own designations for spaces like "stallion barn" or "broodmare pasture", but how does it decide where to put the horse? It's not the first place with a free space on the list, it's not the place with most free space either. At least once moving horses in resulted in pasture overflow, as the small pasture with space for 4 horses ended up holding the 2 already there, then a foal I moved in from the other ranch, and then the foal's dam I also moved in and who was already pregnant (just bred on the other ranch), which results in 5 horses, including the unborn foal. I moved the mare over to the broodmare pasture, then thought I probably should have reported a bug, but couldn't move her back anymore.
So, is there any way to guess where my new horse had ended up this time? I only have like 5 pastures and a barn, and the searching is already getting annoying sometimes

[Argent]

They go into the most empty one.