As an addendum I did just find a Orbx Forum post "Orbx Central with P3D4 and P3D5 on same PC" from May 3rd, 2020. I tried to follow this - and created a P3D4 library folder but when I move things like Orbx Global Base and Buildings HD, TerraFlora V2 it seems like they are being downloaded again then installed. I am missing something - if there is "for dummies" explanation of how to establish a P3D Library for P3D v4 (without downloading) I need it !! Alan