Sorry to hear that Brucklay
I was about to write that yes, she'd be fine with the ram, but then thought - are you confident she doesn't have another, healthy lamb in there?
She'll be a bit miz for a day or two anyway, so one option would be to pen her where she can see and hear other sheep but they can't sniff her bottom. Then, once she feels more herself, you could pop her back with the other mums-to-be. Maybe give her bottom and back-end a jolly good clean with iodine or something first.
As to putting the 8 with the Castlemilks... my only hesitation would be the CMs' horns and how they might be with any new lambs, so I'd have thought you could put them together for a month or so anyway.
Take your vet's advice - there are a number of causative agents, plus 'just one of those things'. You can protect the remainder with Alamycin if it's enzootic abortion, but some of them just have to work their course.
I've just had a look at the Eblex manual. (It's Manual 14, Reducing lamb losses - download it
here.) It says that for enzo, keep them isolated for 4 weeks, so keeping her seperate (but in sight and sound of other sheep) for a few days until she feels ok, then cleaning her up and putting her with the tup for 4 weeks sounds like an option. It does also say that infected sheep will be carriers, so check with the vet but that sounds to me as though future choices are cull or vaccinate.
However, the Eblex manual does also say that abortion is usually at full-term. If earlier, you would expect the foetus to be mummified.
I think the vet will be able to do blood tests after lambing that will identify any infections from the antibodies in the ewes' blood. However, I don't think these things are infallible - we had this done on the moorland farm, and nothing was found - but for sure we'd had some kind of agent, we'd had quite a few very sick aborted ewes that year. And I had absolutely definitely kept track of exactly which ewes it was that should be tested.