have you tried putting little pieces of food oaround your door? this
might make them warm up to you. sorry if this doesn't help!

A feral mother cat with kittens is probably something you should have
Animal Control or your local Humane Society handle, ISTM.

But if you'd rather do it yourself, here's how from
http://www.atlantaanimalalliance.com/aaa/howtotrap.htm:

"Some cats can be trapped immediately, but more wary cats will need to
be conditioned to the trap.

"To do this, feed the cats daily at the same time in the same location.
Place a trap in the area you feed. Open the door of the trap and secure
it open with a piece of string or wire. Put the food outside the trap,
but near the open door. Each time you feed, move the food closer, then
into the trap. The door should still be wired open. You can also use a
cage, medium or large pet carriers, or a cardboard box.

"Set the trap at the cats' normal feeding time. You may want to withhold
food for one day prior to trapping to ensure that the cat is hungry
enough to go into the trap. Line the bottom of the trap with a thin
sheet of newspaper and put some wet food, mackerel, anchovies, or tuna
in a paper or plastic dish set all the way in the back of the trap.
Trail a tiny bit of food inside the trap from the front to the back.

"To avoid accidentally trapping skunks or raccoons, try to trap before
dark or just after dawn.

"After the trap is set, hide out of sight - in your car, behind bushes
or trees, or anywhere the cat cannot see you. Once the cat is trapped,
approach quietly and cover the trap with a sheet or towel. This will
quickly calm the cat down....

<>[For trapping kittens] "It is best to use a kitten-sized trap. If you
cannot find one, tie a string to the door of a plastic pet carrier. Then
run the string through the inside of the carrier and out the holes at
the back. Set a brick or something heavy behind the carrier so it will
remain stationary when you pull the string. Hide out of sight holding
the string. When the kitten enters the carrier, pull the string and hold
tight so she cannot push the door open. Keep the string taut until you
latch the door.

"If you are trying to catch a mother cat and her kittens, first catch
the kittens and place them in a plastic pet carrier. Then set a humane
trap and place the carrier with the kittens behind the trap. (The door
of the carrier should be facing the back of the trap.) Cover the end of
the trap and the whole carrier with a sheet or towel. The food and the
sound of the kittens crying will lure the mom cat into the trap."

HTH.

Oh Dear. It seems that you have a problem on your hands here. You have
fed them, but never interacted with them? The trap is one idea. If you
don't feel able to do the trapping bit yourself, are there no agencies
that you can call in to trap them for you.(human society), so that you
can @least have the chance to get them to interact with you over a few
weeks or so , then you will have the confidence of the kittens, if not
the mother -which will enable you to handle them enough to trust you
and other humans that come into contact with them.

Earning thier trust Will not happen overnight, but you can achieve a
basic trust you need to allow them to be placed with your cousin ?
Then perhaps she can spend the time that they need to become sociable?
Just a thought?!
S;o)