No advice, but I'm sorry that Fran has EC. Sending lots of vibes for her. I guess you will need to treat all of your rabbits now.
The vet didn't mention that but I guess you are right. I don't know the dosage for Zippy as he hasn't been weighed recently. Will see if I can chat with one of the vets or vet nurses tomorrow. Fortunately, I am not working at all so could take Zippy in if they need to see him.