Some notes:
1. You can't make one .esp for master of another .esp. To do that, http://cs.elderscrolls.com/constwiki/index.php/De-Isolation_Tutorial.
2. If you're using cosmetic mod already, you can edit it for your own use. However, as I said before, some cosmetic mods do it already, though you need to check the plugins if it adds custom hairs to beast races.