If you breed your current does to a Rex, you will get normal coats on the offspring. The coats might be a little denser, and maybe a little softer, but the gene causing the Rex coat is recessive, so both parents have to have it for the offspring to get it.
The Rex has commercial type, so the potential as far as meat certainly won't suffer. I've never tried tanning pelts myself, but I've heard that the pelts of fryers don't work well (the fur is rather thin, and the texture isn't so great). By the time a rabbit is old enough to have a really "prime" coat, the meat is tougher, and the rabbit has passed into the "stewer" class.
If they want the Rex fur, they can breed them keep a baby, breed it back to the Rex, then if the coat is not to we're they want breed that baby to a non-related Rex buck and you should be good. But you should be fine by just breeding daughter to father.