Having trouble getting my feral settled indoors...

Hi everyone!  I am new to the site, found you all through Stray Pet Advocacy and love what I have read so far.

Last spring a feral mama cat had kittens under a neighbors shed, and at about 8 weeks old I was able to grab two of the kittens and bring them inside.  They have grown into wonderful, loving, well-adjust indoor cats.  My 3 older cats warmed up to them after a few months and they have a great relationship now.  I continued to feed Mama and the 2 remaining kittens, eventually the kittens became less afraid and even let me pet them occasionally.  Then, the day before Thanksgiving one of the outside kittens decided to walk right in and make herself comfy inside!  I was thrilled   The first few days were good, all the cats seemed to ignore him and just go about their business.  The feral found a nice hiding spot, came down to eat in the morning with all the other cats and even used the litter box right away.  Thought I was in the clear....boy was I wrong!

The last month or so the feral has stopped coming down to eat in the mornings, so I have to bring the food up to him.  Not that big of a deal, but I wonder why the sudden change?  Also, my older cats are starting to get a little nasty with the new kitten...they chase him, but dont actually hurt him.  His litter mates are relatively friendly with him, but not playful.  My friend who is a vet suggested Feliaway, so far it has made no difference in their behavior towards each other.  The feral comes out for me when I bring his food up, and we have some one on one time where he lets me pet him.  Like I mentioned, he was using the litter box just fine, but this morning he pooped on the bed in front of me when I brought his food up!  I was shocked!  I put a litter box in his safe room afterwards, but am not sure if he has used it yet since I am at work still.

My concern is that my older cats behavior towards him is preventing him from getting to the litter box, and making him uncomfortable to come downstairs and eat with everyone else in the morning.  Also, he has not been neutered yet...could this be a reason my cats are tormenting him??

Any advice from someone who has been through this before would be greatly appreciated!  THANKS

PS - Mama has been spayed already

My first thought is that the cats were not properly introduced to one another.  You must remember that cats are very territorial.  The new cat is a newcomer and even though he has been in the home for a month, things are not settled territory wise.  The new kitty should have had a room of his own for awhile to allow him time to adjust to indoor living then time to meet each of the other cats.  When cats are not introduced properly this is the behavior you can expect.  The new little one is being bullied and is now afraid.  You can try some Composure liquid Max that is mixed into wet food.  You can use it on the new kitty as well as those who are bullying the cat.  It takes a week or so to work.  I would double to dose for awhile as well.  The new cat needs to feel safe and needs a place of his own. 

How many litter boxes do you have?  The golden rule is to have one litter box per cat + 1 extra.  The new kitty needs to have access to a litter box at all times. 

Here are a few articles on cat to cat intros.  It might be too late, but there might be something you can pick out that would help.

http://www.catbehaviorassociates.com/a-simple-little-trick-to-use-during-new-cat-introductions/

http://www.aspca.org/pet-care/virtual-pet-behaviorist/cat-behavior/introducing-your-cat-new-cat

http://jacksongalaxy.com/2010/10/01/cat-to-cat-introductions/

http://www.thecatsite.com/a/introducing-cats-to-cats

Thank you for taking care of these kitties and the Mama too.  You have given them a nice loving home.  With a little work all will be happy soon.