So I got into an argument over exactly what constitutes line of sight and cover for a FUBAR deployment
I was of the mindset that as long as a unit was in/on terrain that provided cover, this was acceptable. My opponent stated that they must also have a blocked line of sight between units in cover. In particular there were two partially ruined buildings which had walls "cover" on two of the four sides- these walls did not block line of sight between the two pieces of terrain therefore, if my oppenent deploys into one of those pieces of terrain first, I cannot deploy into the second piece of terrain because it did not provide cover from the direction of my opponent's units.