How is it possible that you can say: a birth of a child, a funeral of a parent... I would say: the birth, the funeral...There is only one...Am I right?
It is very hard to go to a funeral of a parent. A birth of a child is something magnificent. Correct??
Here are some I might use 'a' for.
"You don't expect to see a birth of a child at a rock concert." (You could use 'the')
"It's always sad when we have a funeral of a parent." (You could use 'the')
It might be correct to say "the X of a Y" in most cases. My point is that this doesn't make it impossible to say "a/an X of a Y".