Currently, there is/was confusion on how to get a rhino mount. The stable is used to train a horse mount. However, a rhino calf will not work in the stables. Instead, the calf must be placed in the animal pen and the player must hope that the resulting adult rhino isn’t anything special. My dreams of riding a white or black rhino were dashed when my first two calfs matured into white rhinos and there was no saddle option.
So, my suggestion is thus:
- train all mounts in the stable
- train all non-mount pets in the animal pen
No need for recipe changes or disabling recipes or forcing all grey rhinos to be mounts or inconsistent training locations.
If a player wants a pet rhino, the player may place the calf in the animal pen and always get a fighting pet rhino, with a chance of getting any of the combat pet varieties.
Should that player want a mount rhino. Use the existing stable to train the mount rhino with only the variety of rhino approved for use as mounts.