Because I use 8 different mods made by myself and others I installed RTW then RTW1.3 then RTW1.5. This I installed BI and BI 1.6. I send these to a zip file then create different folders like "Custom RTW mod". Then I extract the RTW zip to these folders and install the mod such as RS. It is best to zip when you are in the main area of your RTW folder where you see the folders data,preferences, RTW.exe, etc. Then you can have tons of mods all at once. Of course I have a 100 GB hard drive. You might not be able to use this many mods on a smaller hard drive.