HGG Community Forums

You will need to purchase an entirely new barn that is bigger.

1) You can save up, purchase the bigger barn, and still have your 15 stall barn. 2) You can sell the 15 stall barn and get part of your IVs back to put towards the bigger barn. 3) You can purchase another 15 stall barn, and keep your existing 15 stall barn and have 30 stalls but split between the 2 barns.

I can't remember for sure, but I think if you sell the 15 stall barn, the horses will be automatically shifted to your primary barn. Even if you don't have quite enough stalls in there it will overstuff your barn and some of your game features will be limited until you find stall space for the extra horses.