I know that you can that with a sim. In you don't even need to shift+click on a sim in order to do that if they have a high enough level in the wellness skill. But I always assumed that a sim needs to be at a high level in the wellness skill in order to do that, shift+click on them to move them to another location. And here's another little obstacle, say you get the pet or pets up there. What if the pet or pets want to go outside? You would have repeat the process again when ever they want to go outside. And then you would have repeat again in order to get them back in the apartment. Now I'm not trying to rain on any one's parade here. But I think that it would be best to some how add stairs up to the 3rd floor and just skip the whole cheating process of getting the pets to the 3rd floor apartment. But that's just me.
