hi mom yes put dirt in the tray and she may be more inclined to use it as that is what she has been used to recently,
the two kits who are still not friendly, you need to get a cage for them, split them off from their siblings, as in a bunch they will try to get away with not being handled, put on gloves and make sure your clothes are nice and thick, and take each one one at a time from the cage and cuddle them close to your body so they cant wriggle and just basically hold them and talk softly to them, hopefully as they realise they are not going to be harmed they will start to relax,
feeding treats while in your arms will help aswell
11 weeks is definitely within realms of being tameable.
talk to them when you go near the cage i do baby talk sounds daft but low high range voice works,
hopefully the cats home will be able to lend you a cage
i would send the friendlier ones to the rescue and ask them to let you foster the non friendly ones for a couple of weeks longer on the understanding that they will take the other two when tamed
sorry trying to think of everything to say.
the two kist i have at the moment are 13 weeks and while not as feral as yours very timid due to not having had any handling, and what i have suggested above has turned them from hissy spiity kits to little purrers in less than a week
you mainly need confidence when handling them and not standing for any daft kitty behaviour let them know you are not scared of them as they will feed from this and it will make them more nervous ,
hope this has helped