Marion - let me encourage you. If you feel you must write this song then do it.
I'm with a similar problem. My youngest daughter was born on December 23, a fine Xmas present to the family.
Years later I found in the family history, that we had another birthday on this day, in the 1790s, but a stillborn baby. Imagine the terror I was in - it might have happened to my daughter, too. And imagine the parents' feelings of despair on Xmas! It's now for some years that I try to write a song about it, but I still got only a few verses till this day. I don't know whether I shill finish it sometimes.
Your song is about a human experience not so rare, and it fits the only three themes good poetry is concerned with: birth, love, and death (R. Graves). Nobody will know the persons about whom you write, and in no matter you should be ashamed to write, especially if you do it well.

Wilfried