Second FS9 Install: Some Questions

[FSMuseum]

I've been reading up a lot on how to do and what the benefits are of a second installation of FS9. Like many here who have done the same, the goal of my second FS9 is for classic simulations. Reading up on it, I've learned how to do it, but it begs a few questions in my mind:

1. Say that on my already installed modern FS9, I have Ultimate Terrain and GEPro installed. Do I have to have a second installation of those two addons for them to work in my second FS9?

2. If not, then how could those two programs differentiate between the two FS9's?

3. If something happens to one FS9, will it affect the other?

Thanks all
Chris

[chris_c]

Each of my FS9 installations has its own unique executable and Language.dll files:

FS9 with Golden Wings addon scenery (up to about 1945) = FSGW3.exe (uses the Language.dll provided with the Golden Wings download)

FS9 Silver Wings (post WW2 through 1962) = Silver Wings.exe (uses the Language.dll specifically written for FSSW)

FS9 Stock (post mid-Sixties through present) = fs9.exe (uses the stock Language.dll)

Presumably you can point these external programs to the FS9 executable when they're installed? I don't know anything about them specifically but those third-party addon programs that I do use need to be duplicated (generally by creating new installations from scratch) and pointed at the specific FS9 installation. Thus I have three separate FS Passengers installations but only one Airport Design Editor that gets pointed to whatever installation as required. FSMetar seems to be able to find all of the FS versions regardless of what executable is in use.

A separate FSUIPC needs to live in each Modules folder, I have the registered version and each has its own unique settings but this also applies to the unregistered files.

If done correctly, all installations should be entirely stand alone, at least that's been my experience.

Chris