problems with two fixed cats

i have a problem i have two cats that have been buddies for along time and we had the malel fixed awhile back and the female just on the August 16th, well the male has been hissing at her i've read its because of the vet and the animals that was there, i just tried baby powder yesterday on them both and the male is still hissing at her, i dont know if you have to put alot of powder on them or not i cant smell it on her,so if there is any advice i would love to hear from you and how long does this hissing last it breaks my heart to see the female trying to walk to him and then stops because she doesnt understand why he's hissing at her. Thank you

Yes, this a common reaction after vet visits. Instead of baby powder, I would recommend scent swapping. Either rub a towel on one then the other or brush one and then the other. Basically mingle their scents as much as possible. It will get better I promise you.

For me it is my female that hisses at the male when he comes back from the vet.  The male doesn't do it when she comes back.  It takes two or three days for it to stop.  I guess it takes that long for the vet smell to wear off.  I used to take them to the vet together but now Patches goes more often so that's no longer an option.  I know it is disconcerting but they will be okay.

i have another slight problem, we have a total of 6 cats; 3 bigger ones and 3 i would say 2 or 3 months old that we brought into the family from outside. which when we found them they was smaller we have had them for about 2 months i would say, the question is how long for one of the older ones to accept them? the one we fixed the female is the one that isnt accepting them yet, at first she would reach her paw out to them and hiss and growl but now she so far just hisses and a little bit growls at them. i would like for them to get along u know, will she ever accept them? i just feel bad that we brought into the family new members that her home was invaded and the male hissing at her after being fixed that she probably feels bad and just unloved which we give all of them love and attention so if anybody can help it would be appreciated thank you, Carrie

How did you do introductions? Maybe you could try re-introducing them like in this article? http://www.thecatsite.com/a/introducing-cats-to-cats

Unfortunately, the female may never love the new arrivals like you want. Peaceful co-existence may be the best you can hope for. As long as there's no actual fighting, it's going pretty well. Lots of luck to you.