S.F.
As a pediatric oncology nurse I have a suggestion. I recommend that you donate to a cord blood bank. This will allow your cord blood to be used by someone who may need it now, plus it's free. If one of your children were to need it it could still be there as well as having other options. Many people tout that it's great for if your child gets cancer and needs a transplant. Most children who need a transplant need to have cord blood or bone marrow from a relative but not themselves because the bone marrow is where the cancer is (cord blood just replaces it with the same marrow that "went bad"). So in other words, you would truly be saving the cord blood for only your oldest daughter, even then there is a possibility that it would not be compatible with her. Your children only have a 1 in 4 chance of matching
HLA typing. That being said I think that is an expensive undertaking when there may be a child that could use it now..
Here is the link to the info from the national bone marrow donor website. There is a ton of info there and that can help make your decision one way or the other easier.
http://www.marrow.org/HELP/Donate_Cord_Blood_Share_Life/i...
Also here is a cord blood bank that gives you the option to store or donate. They do tell you why to store; however, bear in mind as I said above that several of the listed leukemias can technically use cord blood. However, typically it is not that child's.
http://www.cryo-intl.com/options/
Hope you find this info helpful.