Intro & Split Cage.

Credit for Babymoli
Intro no need bigger room. Just need a split cage. The tank must have only bedding, water bottle & food bowl. Other things must be out. Change your bedding & wash your tank with detergent before intro-ing. Put the new one inside the split cage & inside the tank. Once you are free, you can start intro them by placing them on a place around 2ft wide such as table one by one. First will be the new fella, then the old fella which you feel is the less dominant one. Watch them carefully. If you see them sniffing each other & don't move, use a cloth to separate them. Once you feel they can get along after few minutes, put in another & repeat the steps till the last one in. If you see the new one like panic then must keep an eye on him/her. If others go sniff him/her & he/she runs away, others will chase him/her. So separate them with cloth.

Split Cage: