Posting Yahoo/other support groups links is fine here - it's the posting of other cat discussion forums ("competitive" sites) that's frowned upon. Please do post your group's link.
No need to apologize! However, I can't state my case for getting her on here any stronger. I'll let you figure that one out. Perhaps print out this thread and pass it along to your brother.
The plain facts are that all Vets are not "created equal"....are not sufficiently knowledgeable about anything feline that goes beyone everyday, run-of-the-mill "stuff". Difficult to diagnose cases, chronic conditions and the like often require extra work by the Vet: research, networking etc etc....these are things that are most often "non-bill-able" to the client, and so, not worth the Vet's time and effort. That's often why, when a cat is diagnosed with FeLV or CRF, the recommendation is so often, eithanasia. Pathetic!
As katlover13 said, anemia can have a number of causes, including "unknown". It takes a competent, ethical Vet to stick with the diagnostic trail. Frankly, however, I just don't "get" the waiting period for the FeLV test. I'm already very suspicious of that Vet....with the caveats of realizing I don't know the balance of the story - and, that the cat is being medicated.
As well, that process may very well be expensive...and, that may (unfortunately) be a consideration for your brother.
Now that you have a "heads up" about the possibility of a recommendation for euthanasia with a FeLV diagnosis, I suggest you forewarn your brother. Sometimes that diagnosis is "couched" by Vets in such absolutely awful terms, that the parent/owner is made to feel guilty if it is not accepted. The undisputed facts are that many kitties can, with appropriate treatment, go on to live happy lives.