Occasionally, you'll see a person or agency credited with providing hair and make-up on a particular release.
Example: Yukari Nohara provided hair and make-up design on Nouvelle Vague
Sometimes there will be different people in each role (one for hair, one for makeup), as is the case on Britney, where Kevin Mancuso is credited with hair and Kevyn Aucoin is credited with makeup. For cases like these, it might be best to have tiered ARs like we have for design and illustration.