Why do you want to reinstall to make them work together ? Are you seeing any issues ?
When I installed Pets, Supernatural stopped working and since I installed Pets, I can never play Supernatural. My PC requires Sims Pets CD to play Sims and when I open the start programme for Sims, it says that Supernatural isn't installed which it is. So I just thought I would uninstall Supernatural, install Pets and then re-install Supernatural because I want both of them to work when I'm playing Sims...
Then try manually deleting everything: http://simswiki.info/wiki.php?title=Game_Help:TS3_Uninstall
