This is a very strange story, and I can't help fearing a Josef Fritzl type scenario:
https://www.bbc.com/news/articles/c5115e7k2eno
So much so that I can't quite understand why no journalists seem to think it: on the BBC this afternoon the journalist said something about how them being full siblings meant that, unusually, this time people were concerned about the father too. I mean - maybe. But that's not what it's shouting out to me - I'm wondering if the babies were not, in fact, removed from the mother, and whether she is being kept prisoner somewhere by whoever is fathering these children.
I really hope there's a proper search going on for her.