lid wrote:

We have 2 queens who have had litters on our rural back porch.

Why don't you do the humane, responsible thing and spay the female
cats?

They are not queens. They are female cats, and they should be spayed
if nothing else.

All cats can be caught in a raccoon cage if you train them to go into
it for food. Put food in the cage once a day for a week or two. They
will get used to it, and then on the last day (when you've made
arrangements with a vet), you put food into the trap (on a paper
plate) and set the trap. They will go in, and get caught.

Have a large blanket or sheet ready, and quickly cover the trap with
the sheep. Cover it completely, and then put the trap in a garage or
quiet place until it's time to take the cat to the vet for your
appointment.

Some vets have a box large enough to put a raccoon cage into it and
apply some gas to knock the cat out, and then they can take the cat
out and spay it. But most times, after spending the night in a dark,
quiet place, even wild cats can be docile enough to remove from the
cage and be handled by a vet.

We are concerned that the neglectful queen's kittens may die if
left alone like she is prone to doing.

Why did you let the situation get out of hand?

Why didn't you get the cats spayed before (or while) they were
pregnant?

Now look at the situation you have to deal with.

I am seriously considering putting the two neglected kittens
into the other queen's box while she is out of the porch.

That will probably work.

And stop using "queen". Cats should not be identified based on their
slang reproductive labels.

It is not desirable, or humane, to allow any female cat to be (or
become) a "queen".