Pretty sure you keep them. My brother rolled his 2nd linked account this way
No i just created a seperate account to raf with, decided i wanted my mounts and shit on that account as well. opened a ticket saying i wanted it under the same battle.net. had to provide picture id and the accounts have to be under the same name. you keep all raf benefits.
edit: quicker to go straight to livechat than to ticket it.