SIMS3 Into the Future expansion pack

I bought the SIMS3 Into the Future expansion pack through Amazon.  When I select it to download in Origin, I get "DLC Compatibility Alert"  It seems the base game for the DLC was not installed through Origin.  For the Sim3 Into the Future Expansion pack to work  you need to:   (basically uninstall and reinstall)  First of all WTF, this process is horrible.  Second how do I know if I uninstall Sims3, I will be able to reinstall it from Origin.  Is there a way to test the product code to ensure I won't be both without the expansion pack and without Sims 3?