I would vaccinate when I brought them in for blackleg now since you have had trouble and would probably go to a intra nasal vacc for the respiratory. Then when you get through buying you could come back with a ML vaccine. I have a vet friend that is big on this and it is supposed to boost immune response and be easier on the calf too. I don't think the vaccine caused the blackleg and he was going to get it anyway. I think if you had vaccinated 4-6 weeks earlier he would not have got it either. I think on the little fly weights they have not had the best life anyway and if they had they would not be sold at the size they are.