Need advice on how to release feral cats at new location

We had a feral mother cat have kittens under our storage shed where I work.  My boss would have just had them trapped and turned over to Animal Services.  A group of us began feeding them.  Eventually we trapped all three cats (the mother cat and two kittens).  They have lived at my house for four months, confined to one room. All three have now been spayed/neutered and given their shots by a low-cost clinic.  Most of the time they hide under the sofa in that room but they do come out sometimes.

I know that it's recommended to release where they came from... but this is not possible... as they were fed at this location/my workplace and my boss will want them removed again.

I would be happy to keep them as outside cats (I have five of my own already).  How can I introduce them to my backyard (which they have never seen) and let them know they can return for food?

Any advice is so welcome!  Thank you.

 You will need to first have some way to confine them in large cages for several weeks on your property while they get used to that being their new territory.   otherwise they will probably not stay but will try to make their way back to where they came from.

Here is an article from Alley Cat Allies on safe relocation of feral cats.   http://www.alleycat.org/page.aspx?pid=636

& here is a pdf with a bunch of different examples of  what people have used for this  http://www.kingcounty.gov/~/media/s...s/Barn_Cat_Acclimation_Facility_Examples.ashx

  Ideally,   you might consider fencing your backyard with a cat fence to keep them safely confined in your yard and prevent them from bothering neighbors.

I agree with maewkaew: the kittens need to be confined for at least two weeks (preferably longer), or they will try to return to where they were found. Feed them in the confined box/shelter so they associate the shelter with food (a good thing).

Thank you so much.  I did receive some advice about getting a large dog crate type enclosure and keeping them for about three weeks in that in my backyard.  I appreciate getting multiple opinions to reinforce this idea.  I did have the cats microchipped and also they have the ear notches.

Thanks for looking out for this cat family!

Thank you so much again.  The articles you sent were so helpful.  I have some ideas already.  I am in Florida so the temperature is not so much of an issue.