Hi, again, Rachelle, I suspect you may be right and that when you picked up your kittens, they were several months old and beyond the stage when they could be easily socialised (but don’t give up hope). The Messy Beast website is the best on the Internet for information about cats and this is what it says about trying to tame ferals:
http://messybeast.com/feralkit.htm
Take it as your Bible, it has the best advice you will find.
First of all, I really admire you for taking them on and sticking with them. I have worked with socialising adult feral cats and it is NOT easy. I admire you even more for sticking with them when you have children, whom of course you don’t want to get bitten. Most people would have given up by now. Your first port of call should be your vet, maybe you have tried this and they haven’t been much help, but I would hope that they would give you some good advice on whether they see your cats ever coming round and on possibly rehoming them to a farm or other safe place, like a good TNR colony, where they could be semi-wild but safe, as a ‘barn cat’. They may suggest a short course of kitty tranquilliser. If you get the feeling your vet doesn’t really care, look for another vet who is good with cats — ask around friends and family for recommendations.
First though, a few hints. As I read somewhere just the other day, when a cat hisses at you, it is warning you that it is feeling uncomfortable and that whatever you are doing (trying to feed it, pet it, handle it, whatever), please stop or it will be forced to get a bit more aggressive. Hissing at you doesn’t mean they don’t like you, it doesn’t mean they hate you. It means, please stop that now because I am freaking out and if you don’t stop it, I will have to move on to clawing and biting and I really don’t want to do that. At the point where you get hissed at, don’t ignore it, just stop, retreat and give kitty some time-out space. Eye contact is a challenge to cats so don’t make eye contact, always look away from them or if you do catch their eye, blink slowly and exaggeratedly, then turn your head away and yawn exaggeratedly. Again, in cat language, this means ‘chill out’.
I think you will have to start again from the beginning and I also think you need to separate the cats into different rooms during this process as they are reinforcing each other’s behaviour and do not need to bond with you as they are bonded to each other. A small enclosed space with a hidey hole they can retreat into (a covered cat bed?) would be the best idea — maybe you can borrow two collapsible cat/dog cages and have each in a different room. Put one in each cage, feed them, change their litter box, give them toys and a scratching post in their cage and a soft cat bed to hide in, speak gently to them (but don’t make eye contact, the sound of a low, gentle voice is your best way to get through to a feral) and let them hide from you when you go near the cage. Don’t try to handle or pet them, just ignore them as you go about your daily lives, but do speak to them lovingly a lot (again, without looking at them). Plug in a Feliway diffuser right by the cage. I am hoping that if you are going to be able to tame them, then you should be able to tell in a few weeks if this is going to work. No loud noises or abrupt movements and best to keep the kids away from the cages if you can (but again, maybe get the kids to sit down a little way from the cage and talk to them or read to them, without looking at them). Click the pink ‘Socializing’ tag, read through all the posts and threads — there’s some great advice — and follow the Messybeast page’s advice for feral kittens and cats.
You will see that there are cases where Sarah of Messybeast thinks they may not be able to be tamed, because of genetics and conditioning, and in that case releasing them to a trap-neuter-release colony may be the best idea. I would talk to your vet about possibly doing so as a last resort, but I would NOT release them to the colony where you are. I think they would freak out and the other cats, who already see them as strangers and know their look and scent, might attack them. Do you have any friends living on big properties who have barns or garages where they could be released but still have a warm dry place to sleep and be given food. If you could find a way to make them ‘barn cats’, with kind owners, that might be the best suggestion. If they are neutered and have all their shots, a warm safe place to sleep, food available from a kind ‘barn owner’ when they need it and medical attention if anything happens to them, then this may be the best option for all of you. Such places are hard to find though — your vet may know of someone who could use a barn cat or a safe trap-neuter-return colony — so it may take some hunting down and patience on your part. Please don’t advertise them on Craig’s List or anything similar as ‘free to a good home’, as that’s where people looking to hurt cats often go.
Hope this helps a bit. Best of luck and don’t hesitate to come back with more questions. You have chosen a hard road to hoe but it is worth persevering, at least for a few months longer. I have seen some miraculous results! And if in the end they do need to be rehomed to a colony, they are healthy, desexed and vaccinated — still miles better off than when you found them.