introducing new litter to outdoors and other cats

Question
How, and at what age, do I introduce my new litter of 6 kitties to the outdoors and to my older cats?  The 3 older outside cats are their Aunt, Uncle and Grandma, all altered.  The litter's mother was raised outside but brought inside for her to deliver the babies.  They are now 3 weeks old.  My outside cats are "mousers" and I do not want them to think the kitties are mice and kill/hurt them.  I have an outside cathouse that I put the last litter in at 4 weeks.  They were able to get used to the outside and come and go but I did not have the worry of older cats then.  Thanks so much for your help....

Answer
Susan,

I would wait until the kittens are weaned (5-6 weeks of age).  By then they should have all their coordination, have full use of their senses, and be able to regulate their own body temperatures.

I would not worry about neutered males as they tend to make great nurse maids.  Adult cats DO know the difference between mice and kittens.

Best regards... Norm.