Mother leaving kittens behind?

We adopted a pregnant Siamese mother from the pound, and she had four kittens exactly ten days ago. She has stayed with them almost constantly since then, behind the couch, only coming out to eat and use the litter box. Yesterday, she took one kitten with her and hid in the closet. We assumed she was only moving the kittens and would come back for the others, but two hours later, the other three kittens were still alone behind the couch, mewing frantically.

We moved the kittens to her in the closet, and within an hour, she had taken the same kitten and hid under the bed, leaving the other three in the closet. Now, no matter what we do, she only wants to take care of the one kitten, the same one every time. She always abandons the other three.

I've tried to do some internet research but don't come up with much. Can anyone explain to me what might be going on? And is there anything that I can do?

the only thing i can suggest is maybe confineing her to a samll space , so she cannot move them about , like a large dog crate? make sure she has food water and a small litter pan in there with her.
ps , welcome to the site , someone should be along soon with some more advice.