Many EPs have caused changes to originally base game objects, not just Pets. It's not necessary to offer base game compatible versions, of course, just make sure you have marked your download properly to inform people which EPs are required, so that the objects don't cause problems in their games.
Before you start re-creating your items, you should check if it's necessary. Open each of your objects in SimPE, go to each Object Data, click on the Raw Data tab. Then click on the little icon on the top left corner of that window at says "AZ". Then look at the line at the top of the list. If that line says 0x8b for each of the Object Data for that object, then it's base game compatible without you having to fix anything. If even one of them says 0x8c, you should consider re-creating the object if you want to make sure it works in all versions of the game (unless it's something like a bookcase which you want to have the University specific functions for college, for example).
May I ask please, if I had objects with 0x8c created, is there a way to find out what ep is needed? Can I see it in my packages?
Hoping someone sees this since this thread has not be used since 2008. Question: when making an object base game compatible, most tutorials say to go to the File Table and uncheck all except Include CEP and Include original. What about Include graphic? Most screenshots in these tutorials don't show that option of Include graphics. Isn't that something important?