I already have Pets EP installed, but I wanted to buy the Fun with Pets collection for the two stuff packs it comes with (M&G and Family Fun), which I don't have. But will it mess up the game to install it, since I already have Pets installed? It looks like all 3 games are on 1 disk.

Thanks!

You can't have them both installed at once. You'll have to uninstall Pets, then install the Fun with Pets collection - remember to backup first.

Actually, I hate to disagree with whiterider, but I got Fun with Pets for the very same reason. I already had Pets, but I wanted M&G and Fun with Pets, which I could buy at Walmart, was the only way for me to get it without having to order online and wait for it. When I installed it, there's a screen that comes up with options for what you want to install. I believe, by default, everything came up checked. So, simply de-click Pets and install. No need to uninstall your already-existing copy of Pets first.

Huh, that is weird. I know the usual rule with the collection packs is all or nothing - but I don't have any of them myself, so perhaps that applies to some but not others. Very interesting!

I actually thought it was kind of weird, myself! And I kind of discovered it by accident. I was thinking I'd have to uninstall Pets, but I kind of unthinkingly put the FwP disk in and the install started and then that screen came up -- IIRC, it comes up after you put in the serial # -- and then I figured I was OK. It worked fine when I installed it on my laptop and again when I installed it on my "new" desktop. So...Yeah, that's my experience.

I can only confirm what iCad says: I also already had the Pets EP when I installed The Fun with Pets collection pack, and I didn´t had to uninstall Pets first. In fact when I started to install the game could see that I already had the Pets EP, so Pets was not checked by default in my case.

Likewise, I only installed M&G, after I tried Pets and did not like it. M and G was nice and I liked the hairstyles that came with it.
But I thought M&G was only "Stuff", but it added many new interactions as well.
And then, my computer started to be noisy, as if this installation was the last straw. So I uninstalled again.