Can a ranged attack target a Companion that occupies the same space as a figure? Does the other figure block LoS?

I think not, as LoS seems to count for the spaces between target space and origin space, not the target space or origin space.

--JP

Yes you can target a companion that is in the same space as a figure. The other figure does not block LOS to companions in his space.

Objects, figures, and companions in the same space can be targeted independently and they do not block line of sight to each other.

Also, it has been defined that companions are adjacent to objects and figures in the same space, requiring 1 accuracy. (Objects in the same space are not adjacent, but you are explicitly allowed to attack them while occupying the same space. 0 accuracy is required for objects in the same space.)

Also note that line of sight and required accuracy are determined separately. You can be counting spaces through a different path than you draw line of sight.