"Authorized Resident" vs. Tenant

[Art Maydan]

I'm managing a property with a 4-bedroom coachhouse. I wasn't the one who found or signed the tenant. They're four young adults who seem to be splitting the rent equally, but on the lease, three of them are tenants and one is under the "People authorized to occupy this premises" section. One of the tenants contacted me and said that the "authorized resident" is moving out and here's the info of the person who will be subletting from him. I was going to reply that he needs to go through the screening process and all that, but I'm not even sure how this works legally since the guy who moved out isn't even a tenant. Seems to me the three tenants are on the hook for full rent and the fact that they're getting part of it from this authorized tenant is irrelevant. So is it just a matter of removing him as an authorized resident and adding a tenant? In which case, proceed like a normal sublease with screening but do an addendum instead of a sublease agreement? It's a 4-bedroom house so I'm pretty sure I'm allowed to have 4 tenants, right?

Much Appreciated,

Art