Rainbow, I can't help feeling (and, forgive me, but I can't stop myself from commenting) that it may be confusing for your March 2013 baby to be hearing 'every single day' about another child whom they have never met, seen or interacted with.
I'm all for absolute openness with children. I believe wholeheartedly that they can accommodate the complexities of life, if presented appropriately, in a beautifully simple way. But aren't there particularly good ages to introduce information about their family history which is based on facts of life which are beyond anything they can comprehend from their 'known' world and which are related to big emotions they haven't yet got experience of or the facility to manage? Maybe between ages 3-6, or maybe when you are pregnant again in the future, I don't know?
My worry would be that talking to your new LO every day about your baby who died during birth may introduce something unhelpful into the family dynamic. I'm not sure how you would you want or expect them to react to this continual topic of conversation if they have no experience themselves about the processes that you and your family went (and are still going) through and if it is clear to them that there are very big - and perhaps, to them, scary - emotions connected with this topic. Something to be brought up now and again perhaps, in casual conversation, so that it's very much a part of their family history, but every day?
This is your family, your history, your lived reality and your choice, but I just wanted to play devil's advocate based on my own experience of being a small child having to deal with Really Big Adult Things that, in retrospect, I always sensed (and now know) weren't appropriate for me at that age.