This is a tricky one. I have to say that it's the sort of thing I'm instinctively against, but then when I read more about it I start to change my mind.
I think saying "Designer Babies" makes it sound more like genetic modification of embryos, when what they're doing is screening existing embryos for compatibility with their existing child. Well, you pays your money and takes your choice on that one, whether you agree with the ethics of that or not. Again, I'm instinctively against it, but you can bet your life that if it was my child I'd change my mind pretty quick.
The procedure the second child would have to undergo to donate bone marrow doesn't seem to be such a bad procedure after all. Certainly no organ harvesting going on! Have a look on this page, quite a way down, it talks about the experience of the donor. http://www.childrenshospital.org/cfapps/A2ZtopicDisplay.cfm?Topic=Bone%20Marrow%20Transplant
So all in all, taking into account the parent's emotions, the selection process and the transplant process, it's a whole lot less ghoulish than the newspaper headlines suggest. However, I'm still not sure I'm entirely happy with it, need to ponder some more. I sympathise with the parents though.
ig.