Instructions
Introduce the kittens at a time when you know you will be home for at least three days so that you can monitor them as they become acquainted.
Set aside a separate room for the new kitten(s) with its own litter box, water bowl and food bowl. This room will only be the kitten's temporary home until you have observed that it is safe to leave the cats in the same room together.
Make the kittens aware of each other's presence while maintaining a safe distance between them. One way to accomplish this is to put the kittens in two adjacent rooms and allow them to sniff and hear each other through the door. They can peek underneath the door and see each other and may even be able to poke their paws into one another's rooms depending on the make of the door. Keep them separated for one to two hours.
Allow the kittens to freely interact with one another once you open the door as long as they do not begin to fight. Some mild hissing or displays of defensiveness or apprehension are normal and to be expected, but promptly separate the kittens if they begin to fight to an extreme that they may get hurt. Reintroduce them at a later time when they have had a chance to calm down and grow more accustomed to each other's presence.
Feed the kittens with their own food bowls, positioned at least six feet apart, once you have allowed them to interact without the barrier of the door. This will keep them from feeling threatened by one another.
Encourage a kitten that continues to behave in a needy manner to play with toys while you distance yourself from the kitten. The playful behavior will attract the other kittens to come join, prompting the kittens to play together.
Set up several perching or hiding areas, such as cardboard boxes and cat furniture from your local pet store, so that the kittens can get away from one another from time-to-time. If you set up boxes, make sure to cut at least one hole in each box so the kittens can safely escape.
How to Introduce Kittens
Introducing a new kitten into your home can be a bit of a challenge when you already own one or more kittens or other cats The felines who already live at your residence may feel threatened or jealous of the new furry addition to your household. It is important that you pay close attention to the cats as they become acquainted so that they go on to form a positive relationship with one another.