I think I remember an update from a while back that allowed players to put an entire barn up for LCs at once for the same price. Where do I do this???

Thank you!

Heya! There's a barn view for putting horses up for LC where you enter a price for each horse, but not a way to put them ALL up at once, if I'm not mistaken. ^^;

You can't... You have to copy/paste the same price over and over on the public breeding barn page. It's the same with private sales... I deeply wish what you're thinking of was a thing, though. It was mentioned recently here:

Dang. I could have sworn it was a feature added a few years ago based on Thunda's suggestion