Taming 4 little ferals

Hello,  I have FOUR 7 month old kittens that I'm trying to tame and we are starting to have behavioral problems?

Short story: I was feeding an outside feral cat and was working to tame her for about a year she was/is a tough customer.  She knows I'm not going to hurt her but still wont let me touch her.  Anyway, 7 months ago she had a litter of 4 kittens.  It was September when she brought them to eat and by this time I was allowing her in the house knowing she would bring the kittens to eat.   It was starting to get cold so I let them stay in the house at night and even got a cat door.  The kittens were warming to me... let me sit next to them while they ate, let me pet them a little, and would play with me.  Momma still timid came in with them.  In Dec. when they were ~3 months old and momma was starting to pull away from them. (Also, they were staying inside most of the time.) I took the cat door out and they have not been out side since.  They are living with me in a 700 square foot apartment.

They are all Spayed and Neutered and between the trauma of catching for fixing and one of the kittens getting very sick they started to be fearful of everyone except me.  (We had long adjustment periods after the fixing and sickness)

So, this is where we are today:

I can pet all 4, they know where they can go and where they can't, they will sleep with me on the sofa... not in my lap but up against me.  We play and love everyday. I can kinda pick 2 of the 4 up (one better than the other)

3 of the 4 have even stopped hiding when I come home, the other is still very timid and hardly lets me pet her.  I spend as much time as I can petting and playing with them.   

A couple weeks ago I switched to all wet food and feeding twice a day because their tummies were not digesting the dry food.  They have had much more energy and they no longer have diarrhea. We are all still adjusting to this new arrangement.

Questions:

They all are all terrified of others and hide when anyone else comes in or even walks by.

One has started to play in the water bowl and getting water everywhere... not sure why this just started maybe the food change.

Another has started urinating on the blankets on the bed and sofa.  -- Sometimes she goes in the box.  - I thought this was left over from her illness when she urinated on the bed but now I have caught her on the sofa too.

Another challenge with the one that is urinating outside of the litter box is that I'm not able to get her to the vet for a check up because I will have a hard time catching her.

Any suggestions would be appreciated.

We have two ex-ferals we brought inside at 6 months.  Eight years later, they both hide when we have company.  My granddaughter visited weekly for almost a year before she saw either of them.  (She actually didn't believe we had them!)

What I'm saying is that this isn't unusual.  They may be shy kitties - nothing to do with being ex-ferals.  I would just let them be who they are.

As to the peeing, make sure you use a good enzyme spray and soak the areas where's she's urinated.  It will take the smell away. But you're going to have to do some detective work to determine why she's started this.  Any changes other than the food?    Any commotion can start up this habit - she's insecure for some reason and marking her space.  It could be activity outside the house, too, another cat showed up, construction next door, etc.

Thank you so much for helping these kitties.  You are doing an awesome job.

Ondine gives great advice. Get the cleaner that really removes the smell.

Then it is detective work as to why it is happening. It sounds territorial to me but I am not seeing the whole situation. It could be the food change. It could be a lack of confidence, is this cat that is peeing in places other than  the litter box being bullied at all? Is (are) the litter box(s) in a difficult place to get to? Does one cat hang around or defend the litter box? 

It could be a health issue so it would be best to try to get her in. You mention "left over from her illness". What illness was that? Do you have a vet in your area that can come to the house? She could have some pain, could be something with her paws (is she walking funny?). Is she acting differently? Has their routine been disrupted? Did someone move into an apartment above or below or next to with a cat or other animal? Are there any rodents in the apartment building? Are they able to look outside? Are you on the ground floor?

Are there enough litter boxes? Are they cleaned out frequently? There should be at least 1 more box than the number of cats.

On the former diarrhea, were they checked for parasites and worms? Was an a robust test or an inhouse test? 

It could be a number of issues so detective work will be needed. Keep us up on what is happening and hopefully we can try to help. Good luck.