Actually create new horses is one of the most easier things that exists. .bmt files just contains info of the textures attached to the bms file, so is enough with edit the file with an hex editor for change the textures, same as bsr files, which are just containers. What would really deserver a mention will be if you use a new customized render for horses, but since is the old 60 horse render re-used, is nothing special, in fact is incredible that takes 2 years of pservers since one released new horses. That, together with new bigger potions, would be something finally useful and interesting, since are one of the firsts really custom items, and not copypasta from original Silkroad servers, which is boring.
For give something as a proof, I'm not a bullshit talker, I just attached files for new horses.
[Only registered and activated users can see links. Click Here To Register...]
With this I'm not saying nothing against your team, in fact you are lucky to have nicole on it since she have really nice skills, what I'm saying is not as difficult as you might can think, and it must have to been done years ago.