I would call your local humane society, and if they don't have any ideas, try any veterinarian or animal hospital you know of that has friendly people. Would the Animal Control department of the police force have any traps to borrow? The two older cats, by the way, are not impossible to acclimate to humans - see the http://www.hicat.org , they have a lot of experience, unfortunately, with ferals of all ages. You say they're sweet, and at least used to you enough for you to feed them, they may become lap cats eventually!