Allocate a resource to a client instead of a service

We have clients who are unable to manage the stairs in our building and need to use our downstairs room.  We have created a resource for the downstairs room but do not know how to allocate this to a specific client (as they all have different "services).  Our therapists have their own room on either the 1st or 2nd floor so we do not need to create a resource for those rooms but the therapists do need to access the downstairs room for their clients. We would find it more efficient to allocate a resource (ie downstairs room) to a specific client to save us double booking (or even sometimes triple booking the room) as we can't see straightaway when the room is being used by other clients & therapists