I've heard that the WT itself refers to the elders as "independent agents" (when speaking to non-JWs - which, if you call the Society, the first thing they ask you is if you are a JW or not).
That corresponds with CageFighter's "franchiser" appraisal.
The elders status with the Society is carefully treated in WT literature. To the R&F, they are part of the chain of command. To outsiders they are 'independant agents' who are legally different from WT representatives such as COs and DOs. (I think they also have done something similar with Regular Pioneers. The Society used to assign/approve them. Now the elders do this and simply inform the Society. None of this is overt. But it all appears to be a careful legal stepping procedure to avoid legal ties, under the guise of 'simplification.' Similarly, the Society has the elders write alot of stuff in the columns of their KS manuel when they attend KM school. The objective appears to be so that the Society 'never said' that.)
Incidentally, it is similar with Circuit Assemblies and District Conventions. District Conventions are WT sponsered events. CAs are not. Thus, DCs have an entire WT printed manual instructing how to operate them. Although CAs operate per WT instruction, the paper trail is more elusive.
By the way, if you understand how this works, there is a little room to 'work the system' (very carefully, though). A CO who understands his position vis-a-vis the Society, would never give direct counsel to you on the blood issue, or about using the 'Reccomended Lodging List.' They let their 'stool pidgeons' (the elders) do that. Thus, if you are in a meeting concerning issues sensitive to the Society, and the CO is attending the meeting, insist that he give you the counsel. You might see some serious wiggling.