The kittens may or may not have it; there's no real point testing them until they're six months, because they'll probably test positive before then thanks to their mother's antibodies. (They're approximately five or six weeks old now.)
The vet pushed again for me to terminate her presumed pregnancy, but I'm growing more opposed to the prospect. I'm just not comfortable with the idea. If the new kittens do end up to be sick, I'm willing to deal with that at the time and to have them put down if they are suffering (or are immediately facing it). They aren't guaranteed to be sick; neither, for that matter, is Daisy. Just like HIV, FIV decreases resistance, but it does not directly cause illness.
It is possible to place FIV+ cats, or at least to list them for placement. The vet does not recommend having positive and negative cats interacting, because of the prospect of fighting. He seems to think that high saliva exposure (food/water sharing) is also a possible transmission route. So they should go to a home with no cats or with other FIV+ cats (which placement agencies recommend as well).
I don't figure anyone likely to be reading this is looking to adopt an FIV+ kitty, but I would appreciate any spreading of the word. One adult calico, probably only a few years old; two black kittens, currently approaching six weeks old; an unknown number of kittens-to-come. Those we can photograph are very cute. I would insist on an indoor-only adoption and on spaying/neutering. I would like to place them if possible; being confined to my basement isn't much of a life ... but it is a life, and they are welcome to it as long as they need.