In the central observer's frame, there's only one light sphere. The observers moving to the left and right would be seen moving to the left and right of the light sphere's center, respectively. Note that the central observer could synchronize a bunch of clocks and place them around the surface of this sphere, so they all get hit at the same time. From the other two observers' points of view, these clocks would all give the same time readout when they're hit, but they'd get hit at different times- in the other two observers' frames, the central observers' clocks are no longer synchronized.
Each of the two "moving" observers will also see a light sphere centered around themselves; the observer moving to the right sees the other two observers moving towards the left edge of the sphere. The observer moving to the right sees the other moving to the right edge of the sphere. It all comes down to synchronization being a relative concept just like time and distance intervals.
I think you may find answers to these questions in my answers to the others, as they're related questions.
I know. But I want to pin it all down to one place to avoid possibility of errors/misunderstandings on my part when searching through other posts of your which are loaded with connotations depending on the tension/interplay which you and MD were bringing to the answers to each other there.
I would appreciate it greatly if you could make and relate your specific answer to the specific remaining questions? Thanks!
Edit://Motor Daddy, can you also give me your answer to each of my naive questions in post #81? I want to make comparisons of logic and physics and theoretical assumptions etc which you and CptBork bring to this issue of lightsphere behaviour etc. Much appreciated if you would. Thanks!