I have both FSX and P3D v4.5 on my system. PF3 sees and will link to FSX but not P3D. I have used the makerunways on my P3D install and selected a flightplan from the P3D folder. PF3 will link to FSX with a flightplan from the Prepar3D v4 files folder. I bought this since it is supposed to work with P3D and I'm not running FSX much if at all anymore.
Charles Harris
KTRS The Valley of Speed