This is a tough one.
While I would gladly step-up to the plate and do whatever I could for my children, I sort of side with Linda's, take on the matter.
Where does it stop? Using my own children as examples, I gave birth to 6 babies, so in this scenario, my oldest daughter can't get pregnant, so I carry a baby for her, but she doesn't just want one baby, she wants two or three babies, and then I learn that my second oldest daughter has fertility issues, and so I look to carry a baby for her, but she, too, wants more than one.
The pregnancy and baby years were long and drawn-out for me, but to think about carrying even more babies than I did, and for some one else, definitely would be a tough decision.
I don't even know if I would have looked to adoption had dear husband and I not been able to have children. I've thought about it many times... the "what if", but I'm not so sure adoption would have served as being the right answer for dear husband or me.