Um... Is there a BIL in all of this? It's his family so his situation to deal with (if you can't let it go and wish to "deal" with it).
My very own brother didn't send anything (no card or present or flowers) when my son was born... I was a bit annoyed and so I told my Mum... She told my brother to stop being lazy and so he sent me something. Sometimes some people just need a little boot up the back side by their own family members lol