As long as you keep at least one product for P3D, all the FSDT products MUST stay together, it's not possible to have two separate installations, because our software is not designed to be tied to a specific simulator, but rather using its own folder, without an unneeded duplication of files that in many cases are shared between all simulators, and of course having all the products together make its easier, faster and more reliable to update them.
Case in point, the GSX code ( but also sounds and many vehicles ) is only a single set of files, which are the same in FSX, P3D and ( in future ) MSFS. If we had separate installations for each sim, and you installed all 3 of them, you would have to use the FSDT Live Updater 3 times, to get the SAME files. That is messy and confusing.
You probably shouldn't have installed the Addon Manager in a folder named P3D\FSDT\Addon, because this in the future will only make it more confusing ( even if the software will still work just fine ), if you just used a generic name, like the default C:\Program Files\Addon Manager, or something like D:\Addon Manager, F:\Addon Manager, etc. the organizational aspect wouldn't have bothered you because, if you stopped using P3D, you might simply decide to uninstall our P3D add-ons, and the MSFS addons would still continue to work from the \Addon Manager\MSFS folder. Not that they might not work as they are now, it's just your naming choice was less than ideal, that's why we suggest a different approach and default to a separate folder not related to the sim.
If you really want to "move" your FSDT installation, the ONLY procedure that surely works is this one:
- Uninstall every FSDT product you have. Every scenery and GSX, for P3D and MSFS.
- When asked, reply YES to the question "Do you want to remove the Addon Manager ?". THIS IS IMPORTANT, if you skip this step, you won't be able to freely choose a folder when reinstalling
- Reinstall all your FSDT products again, and this time either accept the default installation folder, or any other folder. If you have a separate disk with more space, just select that disk root, it will create an Addon Manager folder inside, and this is perfectly fine and likely the best choice.