Please Explain When to COMPLETE Phantom Liberty

I do not even care about spoilers in any way shape or form. Have found so much mixed and contradictory information about the ending of this game now that Phantom Liberty is a thing. Simply put, when do I fully complete Phantom Liberty in order to also complete the base game? Currently at the point of meeting Hanako (Nocturne OP55N1) in base game while I am at Black Steel In The Hour Of Chaos for the Phantom Liberty story. Which do I do first and why? Can I do both? I do not want to lock myself out of the base game by doing PL and don’t want to ruin a PL ending by doing the base game. Again spoilers are welcome I just want a definitive answer. No Reddit posts have clearly articulated this and I do not want to screw myself over with 177hrs invested into this game.