People often ask "how should I celebrate the anniversary of the death of my baby(ies)?" Here are a few ideas I have come across.
-a picnic at the cemetary
-releasing balloons with notes written on them
-a letter to your babies
-turn off all phones and go away for the night
-send an email or tell people that X day will be rough on you because it was your EDD, then people can call or send a card and your babies won't be forgotten
-donate things to the hospital where you delivered; either for another loss mommy (a care package with a book and disposable camera) or to the NICU
-donate to a shelter for abused or abandoned children
Hope these helped. I really do suggest you mention to people that your EDD is coming up. Mine kind of snuck up on me and I mentioned it to my husband on his way out the door. His response was, "oh". So it just came and went. No one else remembered either and it really hurt. You can simply tell people that you may be emotional for a few days.
Be gentle to youself as this date approaches and then passes. I have found that the days leading up to milestone days are much more difficult than the day itself.