I am very sorry for your loss. From the sounds of the stargazing and flopping, i would say ibd. As for keeping them together, it is not a good idea. Always keep them in separate enclosures except for breeding. Whenever you get new snakes, they need to be kept separate from an established collection so that they don't spread anything. As far as cleaning goes, I would say soak everything with hot bleach water and rinse very thoroughly. Clean the area where you had them with disinfectant as well. Go back to where you got them and inform them as other snakes they have may be infected if it is ibd. I hope this has been helpful. Once again I am very sorry for your loss.