It's not really that I got this question from downloaders. It's just something I think a lot of people want and never dreamt of it being possible. BUT IT IS!You just need one word: ANYGAMESTARTER (by Numenor)
Those who know what this anygamestarter is, don't need to read further. I think you know what I'm talking about and that you know it is indeed possible.
If you don't know what the anygamestarter is, read this first: http://bit.ly/1mVcs1l
First of all, I didn't say it is possible to have more than one lifespan at once, so in one downloadfolder. Because that's not possible. The game loads one downloadfolder and can only load one lifespan. So sorry to say it's not possible to have a different lifespan in a different household in the same neighbourhood.
As you may have read, in the thread Numenor made, you can make several Anygames or permanent games. So you have The Sims 2 more than once.
Every anygame/permanent game has a different folder in My Documents. So go the folder of the new anygame/permanent game and create a new downloadfolder there like you needed to do in the folder EA Games/The Sims 2 to make downloads work the first time you started downloading.
Put a different lifespan in the new downloadfolder and start the Anygame/permanent game. Now you have a different lifespan than your default The Sims 2 game. So you can play with more than one lifespan.
If you don't want to download the Anygamestarter, here is another hint: You can have more than one account on a computer (maybe there already is one for you, your sibling, parents,...) and that's a different game for every account. So if you put another lifespan in the downloadfolder of another game, you can have more than one lifespan.
I hope this explanation was a bit clear to everyone. If you have any questions, don't hesitate to comment!