Yes you can! There are a few ways to make someone move in with you. Make friends with them and ask to move in when its kinda full to the top (friend bar meter). Sometimes they may refuse, but only because you have 8 people in your family. Good Luck!
Chat with our AI personalities
you have to get a real good relationship with the sim and then when you click on them it will say ask to move in. Hope this helps
You have to go to a computer, phone, or newspaper and then click the "move" option.
Sims have to go potty.
when they move out, they will enter The Clipboard (the place where the Sims are kept after you've made them but before you move them into a house. From there, you can move them into a new lot to play them.
You go to your phone in your house and invite someone over then you choose the person you would like to move in with you and when they get there, if they don't reject you, you go to actions( when you click on them) and then there you go!!(: hope I helped