How long until my adult cats accept new kittens and coexist happily?

it is ok to sleep with your adult cats most of the time. Eventually the kittens will probably come lie with you as well. In the beginning there will probably be hisses etc. but eventually over time the cats probably will take turns. Do not lock them inot the 'safe room', keep it open, so they can start to get more couragsous venturing out and start to interact with the adult cats. It will take time, but eventually they will all at least tolerate each other.

This is very normal behavior. Make sure you provide plenty of litter boxes and food and water bowls to decrease the stress and competition of the kittens. Also, you can put some feliway diffusers in their room to help calm them. Feliway is a cat pheromone to help calm them but it doesn’t work on everyone. Give them some time and hopefully they will start to warm up to each other. I hope this helps!

Good question! You do the introductions slowly, yes. The ideal way is to put the kitten in one room and the other cats in the rest of the house. Once the kitten is cleared by the vet, you will want to put the kitten in the rest of the house and all the other cats in his room. Do this for 30-60 minutes a couple times a day. That way they can get each other's scents. Also, at this stage you will want to feed the cats by the door of the kittens room; feed the kitten on the other side of the door too. So they can smell the kitten and get a reward at the same time. Once that is going well you can use a baby gate to separate them at the door for feeding. After a few days if that is going well (no hissing etc) you can let them all out together. When I say feed them at the door I mean something really good that they will consider a treat like canned cat food, canned chicken or canned tuna. Make it a really pleasurable experience! I also strongly recommend you get some Feliway diffusers. It is "happy cat pheromones" that really works to calm cats down. Use it for at least 2 or 3 months time. Hope this helps. I know it's a long process but it is much better to do it slowly than to cause issues by just throwing him in!

This happens. Cats take time to get used to each other. It can take 6 months before they are either friends or tolerate each other. I have 5 cats, and two of them keep having tiffs when their paths cross, however, in general they get along by ignoring each other. Make sure your new kitty is checked for FIV and FeLV as these diseases are spread by saliva (deep bites when fighting) and also have the new cat vaccinated against rabies. Most cat fights are loud with lots of hissing, spitting and screaming but hardly any injuries....so they sound far more dramatic than they are. Give them time. Eventually peace will rule.

Thanks for using PetCaoch! It’s not uncommon to hear about behavior like Alyssa. It can take a lot of time and patience for them to get along but here are some tips for decreasing stress for Alyssa in the short term. -Feliway- calming cat pheromone- comes in many forms from pet stores or online. 

 - Adding a litter box. Studies show that the ideal number of litter boxes for a home is #of cats +1 . This is regardless of how clean you keep his current litter box. 

- making sure she has plenty of “high space”. The safest (and therefore least anxiety-inducing) place for a cat is up. If you don’t already, get a cat tree or put up a shelf or two that she can go perch on. 
 Feeding them in separate rooms with two or three water bowls throughout the home is also a good idea as perceived competition for resources is a common problem in cats. Best of luck to you and your kitties!

I am not sure what you are concerned about as far as safety. I do recommend keeping new kittens quarantined away from other cats for 2-3 weeks so you can monitor them for any illness that could be incubating. It can take time for cats to adjust. Getting a new cat is like getting a new roommate. Sometimes it is a perfect match and sometimes you can't wait to move out! Giving them time and space to adjust is the best thing you can do right now. You will need to have separate spaces, each space with its own food, water, and litter box. Sometimes using a feline pheromone diffuser can help with stress, like Feliway or Comfort Zone. Here is an article you may find helpful: https://www.petcoach.co/article/5-steps-to-introducing-your-cat-to-a-new-feline/

Unfortunately it's going to take time. That said, there are a few things you can make sure of to help reduce stress, especially in a four-cat household (which is a lot!). Making sure each cat has their own space where they can eat, drink, play, observe, etc without the other cats bothering them can help reduce territorial disputes over these items. Pheromone collars and plug-ins (Feliway) can also be placed on stressed out individuals, or in shared rooms (since everyone seems to be stressed) to help reduce inter-cat aggression. Making sure to have at least one litter box per cat will also help reduce stress and competition over them, and reduce the chances of accidents elsewhere. Otherwise, continued slow introduction of the cats is best. If anyone starts to get agitated or too excited, removing them to let everyone calm down and settle back in is best. Continued aggression and upset may also need a trainer or veterinary behaviorist's help. That said, if your home is very small, four cats may just be too much for everyone to get comfortable.