OK, to get those extra sims on a lot, you can do that fairly easily. It just depends on if you are willing to use a cheat. Just split those sims out into their own household that is not in world. If you know how much the lot costs that you want to place them on, then also transfer that amount of money when you split the household if you can. If you don't want to "steal" from that household, you can use the motherlode cheat to add a few thousand simoleons to that household first then split and transfer the funds. At that point, you should be able to place the sims on an unowned lot.
The 2nd way to do it without "stealing" the money from the household you merged them into is to, again, split them out and don't give them any money. Once they are in a separate household, open the cheat window and use the "freerealestate on" cheat. You'll notice all the red and yellow lot boundaries you see on the map will turn green, letting you place them on any lot without costing them anything. Then you'll need to get them busy making money so they can pay the bills and taxes the next time bill day rolls around.
Hope this helps.
