You can try Twallan's Story Progression mod instead. That one allows you to have the option to enable more than 8 Sims to live on the same lot. It does not affect the entire neighborhood. You will have to enable the option on every lot you play in your town.
Take a look at his
Story Progression mod. The description itself can be intimidating, but the best way to figure it out is to try the options yourself. Test them on a lot you don't care about before you actually use them for your regular families.
I don't know of other mods than Awesome Mod that allows you to move a teen out by him/herself.
*Edited*
Forgot to mention that registration isn't required to download Twallan's mods, but it is required if you want to post there and ask questions.
