Thanks for the additional information. I really appreciate.
So here's my concern....not only are we not positive that they have pneumonia, we are risking damaging their kidneys by giving so many/much antibiotics.
As I'm sure you know, the kidneys filter everything out of the body, and generally they can handle the job...but when you have essentially neonate pups with small kidneys, and you're asking them to process a bunch of antibiotics, you can risk damaging them beyond repair.
Another issue is we worry more about dehydration than anything at this age. Since I'm guessing that they're not really willing to do a lot of nursing, they likely need some IV or SQ fluids to help keep them hydrated so their immune system can fight this infection.
You sound like someone who has experience in this kind of thing in the past, but since you've already lost some of the pups, I feel it would be negligent of me if I didn't implore you to have them seen by an emergency vet, rather than waiting for your own vet to open tomorrow.
If you're not sure where the emergency vet is in your area, you can go do: http://www.vetlocator.com and plug in your zip code and they'll point you in the direction of the one nearest to you.
At the emergency vet, they may just treat the pups as sort of 'herd health'...meaning, they may examine one pup, but then treat them all since they're all sick with the same thing. They'll also likely get some fluids into them. You should make a point to tell them which antibiotics you've already given, since some can interact negatively with one another.
I wish I felt comfortable telling you to wait until tomorrow, but I think it's best for the remaining pups to have them seen today.