I just remember that it was stated in a few articles that rough outlines were being tossed round. As godisawesome pointed out, those were likely "priorities" or "possible guides" for the various threads. In all likelihood these weren't cemented in stone and were flexible enough to be adapted in accordance with the hot potato method they were going for.
Having 3 different directors isn't a bad thing at all. The OT made it work with different directors at the helm of each installment. However the OT had Kasdan in place. So there WAS a sense of cohesion to the narrative. The sequel trilogy didn't have that. TLJ is as 180 degrees to TFA as TRoS is to the TLJ.
As for the Rey/Poe pairing? That was Trevorrow's idea based in the fact that both were pilots. You see a hint of it in TLJ and some of it is still in the first few scenes of TRoS. Mind you, that was when the intention was that Rey was going to be revealed as a childhood friend of Ben who had been sent away when it was discovered that her and Ben were strong in the force and shared a unique connection.